LS 5.3 engine 4L60 trans education please

[Red71gmc]

I am wanting to buy another 67-72 and start a build this winter. I pretty much have the general idea of what I want to do other than engine and trans.

This truck will be a driver but I want to go completely through it. All mechanicals, body, wiring and all. Being a driver, I'm not opposed to add the newer improvements if they are improvements.

This truck will haul normal 1/2 ton truck loads now and again, and will tow a normal 1/2 ton truck trailer now and again (4-5k). This truck would see some miles doing this if I do the build correctly.

I have rebuilt one 350 about 25 years ago. I think with a good book or forum as this I can handle it again. However, the rebuild 25 years ago was all stock and I have no background in mods unfortunately. I am not a beginner nor by any means an expert. Everything I have done pretty much was for utilitarian reasons for business needs to accomplish a needed task or save money to complete a needed task for business reasons. Now I want to play a little.

I originally thought I would go a mild upgraded 350 built by me or a moderate 383 built by someone else with the knowledge of them and how to. The more I read about the LS swaps I'm thinking maybe this would be the way to go in a not so original driver build. Modern engines are nice for a hard driven driver and it seems some of these 5.3's with some mods are doing wonders.

I have been reading up on the 5.3 and have myself more lost then when I started the research. It seems there are a bundle of variations, generations and that's before you get into the transmissions to go with.

I'm looking for some real experienced folks to head me in the right direction for my needs. All the while keeping in mind I'm not a mod builder. I don't ask for much lol. Thank you

[MattDR]

I am currently in a build with the same aspirations. I purchased a complete running engine/transmission with all the asscesories and harness from an 05 Silverado. It’s nice when you can hear and or drive the donor vehicle. Peace of mind. After that you buy swap mounts, I used 73-87 c20 frame stands and dirty dingo adjustable ls mounts for the same year. My truck already had a newer simpler tranny crossmember so that was just a matter of moving for the proper transmission mount. I got the Cadillac CTS oil pan for clearance and trailblazer manifolds. You may or may not have to cut your driveshaft. I am going to have to cut mine. If you want air. Holley or vintage air have a hi mount for the compressor. Other than that. Buy a swap harness or wire your own. From LT1SWAP. Hope this helps

[Red71gmc]

Why do you need a high mount for the air compressor? Are you doing a square body conversion?

[MattDR]

I’m doing a 70. The 73-87 mounts give more adjustability so that you might be able to use your factory driveshaft. The factory Ls truck compressor is mounted low on the passenger side. It interferes with the engine mounts and the frame, if you can get all that sorted out, then you have to deal with some really odd angles for the hoses and fittings.

[brad_man_72]

I haven't had any luck with od transmissions behind a stock 5.3 and pulling a small boat. Many 4l60es an now a $4000 4l80e is overheating.
I'd put a th400 behind your 5.3.
I have a low mount ac from vintage air, the work to make it fit is worth the cleanlieness of the install.

[Macdaddy1]

I kinda went crazy and purchased a TKO 5 speed manual overdrive transmission for my 5.3. I did this because I wanted to bang gears and for the utilitarian trust factor that these transmissions have. I did not want to have to dump a bunch of money into an automatic transmission like brad-man-72. The tremec TKO 500 trans required an external slave hydraulic clutch set up (Novak) that can be used with the stock pedal assembly with a Captainfab brake and hydraulic bracket.

[Jstock85]

Im nearing the end of a 4.8 into an 85 c10. without This forum, you tube, and a rebuild book I couldn't have got this far. Use DD sliders, AC will probably need relocating and oil pan may need to be swapped. Not sure on the 67-72 but my oil pan hangs about 1 1/2 inches below crossmember. Good Luck with your build!

[mongocanfly]

Unless you get a very high mileage LS I wouldn't bother rebuilding it....I had a 99 5.3 with 285k on it and pulled some heavy loads....when I sold it...still ran like new...the LS is not like a smallblock....
the 4l80 is equivalent to the t400 but with od...the 4l60 is like a 700r4...
To make life simpler I would look for a complete pullout from one vehicle...it'll be less headaches along the way...simple mods to a LS can add huge hp gains ...but a stock LS is way beyond most smallblocks...my lq9 dynoed at 344hp stock with headers..my ls3 has around 425hp...
The earlier versions had dbc which is a little simpler to setup...later versions used bdw.
I would try to stay away from. DOD and flex fuel..
on The harness you can build your own or go aftermarket ready to plug in...
Get the ecm unlocked and highly recommend a dyno tune when you get done...a good tuner is priceless when making hp...

[Red71gmc]

Thanks for the information. Sounds like I should try to find a 4l80. Does anyone know if a 4l80 was behind any 5.3's from factory as to try to find a complete setup?

The manual trans is not out of the question either

[MattDR]

Just 6.0’s. 4l80e is over kill in my opinion. I’ve had a dozen silverados and or suvs with 5.3 4l60e’s. Many with 200k plus on factory engine tranny. My Yukon I drive daily is 2k short of hitting 300k. I regularly pull a 6x12 enclosed with commercial mowing equipment. I’ve also pulled several tons on 600 plus mile trips without an issue. If you’re a smart driver when hauling a load you shouldn’t have a problem. If the load is heavy or there a lot of hills keep in third and go on.
Just my 2 cents

[MattDR]

Another thing about a 4l80 is they are 31 spline output as apposed to 27. You will have to have a new driveshaft made. And if you don’t want a hybrid u joint then you will be doing the larger yoke on your rearend. At that point the 12 bolt becomes the weak link.

[Red71gmc]

Originally Posted by MattDR

Another thing about a 4l80 is they are 31 spline output as apposed to 27. You will have to have a new driveshaft made. And if you don’t want a hybrid u joint then you will be doing the larger yoke on your rearend. At that point the 12 bolt becomes the weak link.

Good info. Sounds like you also have had very good luck with 4l60 doing as much or more than I plan.

[Clyde65]

4l80’s we’re behind 5.3’s in some vans up to 3/4ton, 6.0’s were an upgrade.

[ls1nova71]

I dont think 4l80e's were ever put behind a 5.3, but like clyde said some vans had 4.8,s with 4l80e's behind them odd as that seems.

[Clyde65]

That’s right, 4.8’s. My mistake