JonnyTechMech

Hey All,

I know some of you have successfully finished your 5.3 or 6.0 LS swap into a 73-87 fleet side. I’ve read all the threads I could on the trials and triumphs of completing it. Bowtiguy79’s info has very useful. However I have some specific questions about the swap and would like to get anyone’s experienced input on. It’s sure to help others as well. If there is a thread elsewhere or on a different sight, please reply with it.

I’m in the process of gathering parts for a 5.3 swap in to an 87 GMC 2WD. I’m replacing a cracked 305 / Th400 with no AC. The truck set for 4 yrs before I bought it and drove it, then has set for another 3yrs since the block was cracked by a freeze. I still need the PCM, harness, starter, alt, PS pump, trans, radiator, and all hose and lines.

What I’d like to know:

1. What year cluster did you use? ( I have the dummy light cluster and want to replace it with the analog gage cluster that will give me water, oil, battery readouts).

2. How did you over come the speedo cable issue with an electronic 4L60e or 4L80e? (I still need to get the tranny). Don’t have money for Dakota Digital cluster.

3. Did you use the LSx plates that set the engine back 1 inch or the standard from CCP or S&P, ect?

4. Did you get a custom fitted driveshaft or use the stock with no issues? (I’m referring to a 5.3-6.0 w/ a 4L60E-4L80E swap only). Don’t know how much longer the 4L60/80e is compared to a Th400.

5. Did you change anything about the motor mounts with the LS adapter plates? (Did you use stock motor and frame mounts)?

6. If you changed out your stock radiator, what did you replace it with? 2 or 3 core, from what yr vehicle and what did you do about the radiator mounts to make it work?

7. If you did use the stock truck manifolds from the 5.3/6.0, what kind of headers or stock LSx manifolds did you use. Header brand, long/ short and year of stock manifolds from what F-body.

I apologize for a long post, I figured it’s better then nickel and dimming question posts. I will be limited on time to pull out and put in, I’m working off a budget so getting it right the first time is very important, I have limited space to do the damn-thang and I don’t have capacity to fab. Goal is to set the engine in and bolt it down without the ‘HOA’ on my back. Then I can workout the wiring, pluming, etc. Thanks in advance.

popeye

iTrader: (3)

Does the 91 Suburban have an electronic speedo? I thought I read somewhere they did.

jomomma

iTrader: (39)

i gutted my cluster and put in autometer gauges. you can get a nice cluster from covan`s classic. i have the motor mount plates from s&p. the truck had a 400 turbo. when i put the 4l60 in i had to move the trans crossmember forward a little, and get a longer driveshaft made. my stock motor mounts bolted right up to my adapters with no problems. i am using my stock 4 row radiator. ive got longtubes from pacesetter for 99-04 chevy truck installed. passsenger side fitted fine, driver side had to be clearanced.
http://www.putfile.com/jomommajomomma/images

JonnyTechMech

I was under the impressions that the 4L60's were the same size as a Th700r4 and both being longer then a Th400. I figure you would need a shorten driveshaft. Does your truck run a two part driveshaft or one?

Can you put your truck in a manual 1st gear from the column or floor shifter?

What did you have to do, cut some of the frame to make way for the descending header pipes?

Thanks

86 Silverado LS1

iTrader: (2)

Spend some time here and you will get a good idea for what it will take. My .02= Add up everything you can think of to do the swap. I mean everything. Then DOUBLE it and you will be close. As far as the driveshaft, the factory one will work. I wanted my motor low and as far back as possible so I slid the cross member back to where I wanted the motor and the driveshaft was close enough to adjust the motor cross member to make it all work. Then put the trans cross member where ever it falls.

jomomma

iTrader: (39)

yeah, i had a two piece driveshaft. even if i had a stock one i would have replaced it anyhow. i took a small amount of c channel part of the frame away. no problems