what od auto trannie for a 69 bbc 4x4

[coggonobrien]

putting a 396 in my 69 blazer. currently have a turbo 350. what is my best option for an automatic od that can handle 450-500 horsies. also what year would it be out of and will it accept my original transfer case.

thanks,
David

[SeventyOne]

There are a lot of solutions for what you are attempting - here is one.

Use a 700r4 and rebuild it with a Monster transmission kit (to handle the power). You will need to get a different output shaft to mount it to your stock NP205 transfer case but Advance Adapters sells it. The 700r4 is a couple inches longer than a Th350 so you can either move the tranny/tcase crossmember back to accomodate, or move the engine forward (keeping the tranny/Tcase mounts in the same location - no mods needed to driveshafts) which you would likely have to do anyways to make clearance between the 396 and the firewall. I would recommend the DIY4X engine crossmember for this swap.

A 700r4 can be found in many GM cars and trucks in the late 80s and early 90s. Some have a "K" cast into the housing and are supposedly stronger/thicker cast models for HD applications.

[vtblazer]

Originally Posted by SeventyOne

There are a lot of solutions for what you are attempting - here is one.

Use a 700r4 and rebuild it with a Monster transmission kit (to handle the power). You will need to get a different output shaft to mount it to your stock NP205 transfer case but Advance Adapters sells it. The 700r4 is a couple inches longer than a Th350 so you can either move the tranny/tcase crossmember back to accomodate, or move the engine forward (keeping the tranny/Tcase mounts in the same location - no mods needed to driveshafts) which you would likely have to do anyways to make clearance between the 396 and the firewall. I would recommend the DIY4X engine crossmember for this swap.

A 700r4 can be found in many GM cars and trucks in the late 80s and early 90s. Some have a "K" cast into the housing and are supposedly stronger/thicker cast models for HD applications.

- good info.

There are a lot of different options out there, take the time to do the research and then find the one which suites your resources the best.

Guys over on CK5 are having good luck with the replacement version of the 700r, the 4l80e.

[Tom Vogel]

700r... really? Is that the best, man I sure havnt been impressed with the ones Ive driven in street cars. The 'Built" unit we put in my sons 85 blazer was never right either. How about a 460le? Hey I am sure there are alot of smarter guys on here than me.

[coggonobrien]

are there 4l60e/4l80e's that are not computer controlled?

[AJs72K5]

Originally Posted by coggonobrien

are there 4l60e/4l80e's that are not computer controlled?

Both the 4l60e and the 4l80e are computer controlled. They are essentially computer controlled versions of the 700r4 and the TH400 respectively. The 4l80 does differ slightly from the th400 in that it does add the overdrive.

The "K" casting on the 700r4 purely designates the 4wd version with the shorter tail cone required to bolt up a married xfer case.

Personally I swapped in the SS Mega Monster from Monster trans on mine. Specs say it will handle 650hp. I ditched the 205 in favor of a 241 for a simpler swap and a deeper 4low.

Posted via Mobile Device

[coggonobrien]

gotcha thats what i thought. mine is basically going to be a road truck and driving through fields (i farm as well as work in town 45miles away) so no need for anything super crazy, except that it will need to handle my 427

[SeventyOne]

Originally Posted by AJs72K5

Personally I swapped in the SS Mega Monster from Monster trans on mine.

You buy the crate tranny or the rebuild kit? How was the experience dealing with Monster?

[AJs72K5]

Originally Posted by SeventyOne

You buy the crate tranny or the rebuild kit? How was the experience dealing with Monster?

I did the crate tranny. I kicked around getting the rebuild kit to save some $$, but decided building a transmission wasn't in my skillset at the time. I was pretty pleased with the customer service. I got the NP241 from them too. They helped out with everything I'd need to do the swap. Their tech support is pretty decent too.

I just realized that I didn't mention that I got the 700r4.... I didn't want to have to deal with a computer.

[coggonobrien]

were there core fee's associate with purchasing complete units?

[AJs72K5]

Originally Posted by coggonobrien

were there core fee's associate with purchasing complete units?

There was on the transfer case...I think they source them out somewhere else. But, the tranny didn't have a core charge. Looks like they still don't have a core charge and free shipping to biz address helped seal the deal for me --> LINK

[jimmypop]

4l80e

[MB_70]

Will the NP 205 bolt up to the 4L80E or the 4L60E without severe modifications?

Also, I thought / remembered / was told advanced adapters made an adapter (slip collar) that would marry up the TH700R4 with the NP205, eliminating the need to swap the input shaft in the transfer case?

Im planning on building a similiar Blazer, so I am looking for input on this. I am putting a wild 427 in a 70 Blazer and planning on putting a 700R4 behind it. I favored this due to the compatability of the 700R4 & NP205.

[jimmypop]

Originally Posted by MB_70

Will the NP 205 bolt up to the 4L80E or the 4L60E without severe modifications?

Also, I thought / remembered / was told advanced adapters made an adapter (slip collar) that would marry up the TH700R4 with the NP205, eliminating the need to swap the input shaft in the transfer case?

Im planning on building a similiar Blazer, so I am looking for input on this. I am putting a wild 427 in a 70 Blazer and planning on putting a 700R4 behind it. I favored this due to the compatability of the 700R4 & NP205.

88-91 k30 or 1 ton 4L80e came with np205 stock.

[MB_70]

NO KIDDING ...... I never knew that. Im glad I joined this forum. I know engines fairly well ... but shy away from transmissions. I have never owned a 4x4 truck before. "Just incase that wasnt obvious."

Im sure that all three transmissions do not measure the same length. I dont want to have to shift everything so much that it effects driveshaft lengths.

Is there a significant advantage to the 4L80E over the 700R4 (other than reputation)? Im not planning on towing heavy loads, or doing any extreme offroading.

I want to put a capable transmission behind a 427 big block, and I am estimating 550hp with my build (aluminum heads & intake, HEI, and a few other "goodies" inside). The engine is from a 1966 Caprice and it was "rated" at 385hp, but was probably up around 400hp to start with.

[MB_70]

The three Transmissions:

TH350 (In the Blazer now)

TH700R4 (canidate for the Blazer)

4L80E (alternate canidate)

[AJs72K5]

The 205s behind the TH350 and the TH400 / 4L80 have different splined input shafts.
Posted via Mobile Device

[coggonobrien]

gotcha, you think the transmission tunnel would need rework for th 4l80e? also what are guys using for computers?

[cleszkie]

I run a Gear Vendors OD which bolts to the back of the NP205. It can handle all the ponies you want to throw at it and it allows me to split all of my gears in addition to providing OD. A little spendy new (I found mine in a junkyard), but a very, very easy install. Only needed a new rear driveshaft.

[TonyJohnson]

How does the gear vendors work with 4x4? Do you just run it 1 to 1?

[coggonobrien]

how does that work with the front axle though if it is post transfer case

[vtblazer]

Originally Posted by TonyJohnson

How does the gear vendors work with 4x4? Do you just run it 1 to 1?

Originally Posted by coggonobrien

how does that work with the front axle though if it is post transfer case

It also looks really long, how would the rear drive shaft angle be in a blazer with a 4" lift?

[cleszkie]

Yes, you are correct that the front driveshaft is not affected by the overdrive. It only works in 2-wheel drive and has a lockout for when you want 4x4 so you don't end up with two different ratios front to rear. If you need overdrive in 4-wheel, you probably have a death wish! The non-OD speed that I can do in 4-Hi is way more than I ever need.

I actually have a 6-inch lift in my Blazer with a GM 14-bolt rear that further shortens the rear shaft. However, I got a shaft built that runs without any shimmy or shake. It runs a Caddy 300-series slip yoke CV joint at the transfer end and a spicer 1350 yoke at the axle end. The Caddy slip yoke CV is a bit shorter than a typical spicer style CV joint with a fixed yoke. I also rewelded my rear perches in order to point the rear pinion at the transfer output (with about 2 degrees pointing down for spring wrap on acceleration).

It should be noted that these pictures were taken with the rear end drooping, so the angle at the transfer is less than it appears in the pics.

[MB_70]

LOTS of good info on here with the experience to match. I looked up Monster Transmissions and I will be buying the SS 700R4. Its a great price on a bolt in trans with a warranty. (I feel) you cant go wrong. Does anyone know if the NP 205 compatable output shaft is an option from them? I want to retain the NP 205. I will inquire with Monster.

Someone mentioned a DIY4X crossmember ....

Would this be something I need to mount my 427 engine infront of the 700R4 and keep the transfer in place?

How far can I slide the transfer (aka cheat)?

Sorry for the basic questions, Im "far from home" right now and just trying to piece some components together that will work - and do what I want, without looking at the truck.

Hope to get some responses.

[TonyJohnson]

Let us know what Monster says and how it works out. I've got a 10-spline 205 I'd like to mate up to a 700R4.