Dropping ls in 4-wheel drive question

[blazercrazy70]

A friend of mine is going to put a ls in a 71 4 wheel drive we are wondering if anybody has done this. Basically how do you hook up the transfer case can you use the one in the truck now or do you need to get one from a newer truck that was already mated with a 4l80. Looking for some guidance

[DWilbur]

I'm starting the same installation in my 1971 K20. I had to change the motor mount to Dirty Dingo mount do the the LS block is wider that small block. I'm using 1987 bell housing has hydraulic clutch to SM465 transmission and 205 T-case. I had to buy fly wheel for the 5.3, clutch for 1987 Chevy truck. I had to drill out the hole in the clutch do to the metric bolts for the newer fly wheel. I was told that the pilot bushing does not get pressed in all the way do to the distance of the crank and the older stile bell housing. it is 0.40 shorter that older small block crank. check out my build thread last page. the AC will have to be changed out as well as older stile AC compressor. my biggest problem is headers.
http://67-72chevytrucks.com/vboard/s...d.php?t=596036

[71_blaze]

Im in the part gathering stage on my swap right now so you may need a second opinion. In order to use the np205 you will need a pretty expensive adapter that needs modification for the VSS. I decided it just wasnt worth the headache and researched compatible transfer cases. I was able to pick up a np241C (91 blazer) passenger side drop that has the VSS built in from a junkyard for 75 bucks. The tailshaft housing will bolt directly up to a 4l60e, not sure about the 4l80e. You will need a new drive shaft and these are slip yoke. I have also heard but haven't confirmed that some of the np208s may work in that range. If you decide to go that route make sure to pick up the shifter linkage as well.

This is taken from another site i cant recall but may be of help.

All left drop tcase were used in 1988 up truck with the rounded body style and IFS.

1988 V series trucks (Blazers, Suburbans, and k30's solid axle) used either right drop 208s or 205s with a speedo cable.

1989 V series Blazers and Subs used a right drop 241 with a speedo cable

1990-1991 V series Blazers and Subs used a right drop 241 with a VSS

1989-1991 V series K30's with a solid axle are kind of a mystery to me. I believe that 1989-1990 used a 205 with a speedo cable, but 1991 is supposed to have a 205 with VSS.

The cheapest way to go is to use a right or left drop 241 tcase with a VSS that came behind a 700 or 4l60e. That way all the shifting controls work with out special the need for a conversion VSS setup.



*DISCLAIMER** 88-91 V series trucks can be odd some times. The list above is what is generally accepted as fact, but as always, there tends to be stragglers, especially when that body style was being replaced. So you may find an early 89 with a speedo cable 208 for example.

[akdg87]

dakota digital makes a cable driven speedo adapter that converts to an electric signal its 40 bucks and you just need to change the VSS settings in the ECM. I have used this on 3 LS swaps so far, matter of fact one was in a 70 K10 with the older style transfer case (not sure which one) and a NV3500 trans

[Nitis]

A big thing on these swaps is its more than just special motor mounts you have to swap out the whole front crossmember ! not a huge deal and not horribly expensive. $300 from dirty dingo.

This is enough to deter me but maybe I am just a sissy

[mcmlxix]

Check out my Blazer build. in my signature... I have an LSx (LQ9) with 4L80e mated to the stock NP205. There are some obstacles to overcome and choices need to be made. I used custom mounts.. but bolt in options are available.

bolt in crossmember (but needs a small lift for the oil pan to clear the front diff)
http://pacificfabrication.com/63-72-...ssmembers.html

Adapts 4L80e to NP205 (but must upgrade to a 32 spline input)
http://67-72chevytrucks.com/vboard/s...d.php?t=493169

NP205 input upgrade
http://www.offroaddesign.com/catalog...rcaseparts.htm

[Gobuffalo]

If you use a NP205 and the factory adaptor for a TH400 you will need to turn down the lip the indexes into the back of the 4L80E. The output from a 2 wheel drive may need to be cut down a little. The output shaft from the 4 wheel drive 4L80E is too short.

[Gobuffalo]

Off Road Design makes the Magnum Box that is a planetary under drive for crawling that acts as the adapter between the 4L80E and an NP 205.
Big bucks but you get the extra gear. You can use even taller gears in your diffs for better mileage and still have a very low low range while off road.

[Gobuffalo]

Can anybody help?
Just bought a 2003 LQ4 & 4L80E bolted together out of the same truck. When this gets bolted into my 70 Suburban 4x4 with a NP205 do you have to move the rear trans crossmember.
This Burb is an original 4x4, 350,TH350, NP205. I replaced this with a 454 TH400, NP205 that were out of the same 1983 1 ton. I moved the engine to the front most crossmember mounting holes. The trans crossmember had to be moved back 1", so all the holes got redrilled. It wasn't until I remounted the shifters that I noticed they no longer would come thru the hole in the floor. So they got a custom bend.
I'm getting to the point, really.
A 4L80E is longer than a TH400 at the 6 bolt tail shaft flange. With the available mounting options out there, is my only option to move the transfer case farther back or can I put the trans crossmember back in the original position? Or am I just stuck with making custom mounts?

[Gobuffalo]

I know the LQ4/4L80E over all isn't longer than a big block and a TH400. I just don't know what's available "off the shelf" as a true bolt in.

[East Tex]

Originally Posted by Gobuffalo

Can anybody help?
Just bought a 2003 LQ4 & 4L80E bolted together out of the same truck. When this gets bolted into my 70 Suburban 4x4 with a NP205 do you have to move the rear trans crossmember.
This Burb is an original 4x4, 350,TH350, NP205. I replaced this with a 454 TH400, NP205 that were out of the same 1983 1 ton. I moved the engine to the front most crossmember mounting holes. The trans crossmember had to be moved back 1", so all the holes got redrilled. It wasn't until I remounted the shifters that I noticed they no longer would come thru the hole in the floor. So they got a custom bend.
I'm getting to the point, really.
A 4L80E is longer than a TH400 at the 6 bolt tail shaft flange. With the available mounting options out there, is my only option to move the transfer case farther back or can I put the trans crossmember back in the original position? Or am I just stuck with making custom mounts?

You can look at my build thread in my signature. But I left the trans cross member in its original location and installed a Pacific Fabrication cross member/ motor mounts in the front, which relocates the motor slightly. This way you don't have to worry about shifters or drive shaft lengths.