Hello out there. I've been a member for about 3 wks now, but this is my first attempt at a post.

Recently became the proud owner of a one owner 1986 GMC Caballero. Tons of milage, but being a southern California car, no rust. Still wearing the original paint, with the original interior.

Right now, a local speed shop is building a new motor: ZZ4 short block, Comp XE262 cam, Edelbrock Performer heads and intake. Have to use the original carb (Roch QJet) but that's going to be rebuilt by Sean Murphy Induction. Local transmission shop is building a 700R4.

Future plans call for a complete suspension rebuild, and 4-wheel disk brakes.

Ok, question: How many out there are still using the 7.5" 10 rear end?
How about you guys running LT1's? Anybody out there running the 8.5" 10 bolt?

Guess that's it for now.

Look forward to talking to you...

LC

Welcome http://www.poltergeist.us/images/wavey.gif

I'm running an LT1 in my Elky but it's going to keep the 7.5" rear.

Are you in So. Cal.?

Thanks..

So Cal - Antelope Valley, Lancaster. Lived here since 1987.

How's the 7.5 holding up? I'm undecided about rebuilding my 7.5 with posi, 3.42 gears or looking for a Grand National 8.5 10 bolt running the same 3.42 gears.

Your thoughts?

LC

Auto or manual?

A 7.5" will hold up pretty well with an auto even with quite a bit of HP from the motor. The torque convertor keeps the rear from being hammered by motor unlike a clutch. A manual will usually kill a rearend if it's driven real hard. Can't do too many 5k clutch dumps before the rearend will say "bye bye".

Mine seems to be holding up fine even though right now it has the original peg leg in it. I do have an Eaton posi and 3.42 gears waiting to go in when I do a disc brake conversion to it in a few months.

A GN rearend would certainly be stronger but most of the time I see them going for about $700 it seems.

Auto. The previous owner rebuilt the original 200 od tranny many miles ago and put in a used 305. Just barely passed smog when I registered it. Both are destined to be boat anchors soon.

GN rears are expensive, when you can find one.

I'm leaning to rebuild the 7.5 and go with a disk brake conversion also.

LC

Welcome Larry to the wonderful world of Elky nuts !!!
Sounds like you're going to have a nice running Elky when completed.
I installed a rear from a 87 M/C SS ,Its a 3:73 posi 7.5,but I am running a stock 305 in mine.
The question is how much do you expect to spend on rebuilding your 7.5 rear?I would compare the cost between buying a 8.5 and the rebuilding of yours.If the cost is close I would consider the 8.5.

Welcome to a great site. th350 with a shift kit here. Rebuilt the 7.5 a few years ago with a 3.23 gear. Works great for me.

Hi LC! An welcome! I have an LT1 in the vette...but "only" a b&s 350 with ZZ9 in the elky. I've kept the 7.5 (for the moment). I've only had her for a few months now....We'll see how long it lasts. :lol:

Welcome to the board LC.

I have an 80 that I am doing ground up on, and have been for a while, its little 7.5" got a new set of Richmond gears (4.11:1) a new PowerTrax and I am running it behind a 355 producing over 400 Hp and over 400Lb/ft of torque and a 700R4 non-lockup Performance built Transmission. I haven't hammered down exactly the size or stall speed yet but I don't really anticipate a problem from it. I have been warned by a good friend that I could end up very disappointed when it gets trashed.

For now, I'll take my chances. I don't anticipate a problem. The factory ratings on the little 7.5"s is about 340 / 350 Lb./ft. of torque. Its got all new components except the axels and C-Clips but all the rest is brand spanking new. The LS1 produces about 380 (vette version) HP so I would expect that you wouldn't have a big problem with it.

A word of caution though. BOP rears that have the 7.5" ring gears are weaker than the Chevrolet versions of the same rear end. The GN Rear end only has to deal with the boost on a running start, not at the line. Its probably a good rear end but according to the things I have read not as good as the Chevrolet version. So be careful which one you decide to use if you stick with the 7.5". If you stick with what GM stuck in there then I would say that you'll be fine but that is my opinion.

Good luck and again Welcome to NECOA / ECC.