Alright guys, I'm back after a short hiatus, but I am getting pretty close to being able to finally do my V6 to TPI swap. The engine will be finished soon. Heres whats going on with that:

99 Silverado 350 Roller Block
Brand new 906 Vortec Heads
Vortec TPI Base
Stock plenum/runners
LT1 Injectors
Full Roller 1.5:1 rockers
.30 Over Bore to 355
9.5:1 or so compression
All brand new

I was looking to go to a local transmission shop to get the 700R4 that I have that I got out of an 87 IROC built to work for what I need, but looking at ProBuilts options, I think I would rather buy new from them and save the frustrations with the local shop as I have heard nothing about their reputation. I know ProBuilt is good stuff. Probably won't cost too much more either.

Still haven't decided on what transmission to order from them yet though so I need a word on that. I want the transmission to be able to handle the power all day long for many years to come, so I am more tempted to buy the top of the line model rated at 750hp as a good overkill to make sure it will last.

But then after I decide on a transmission, I am still stuck with the stock 7 5/8ths rear. My car is an open geared 3.23 right now, but I will absolutely be switching to a posi before the build is done. And that is what else I need to know about. What should I do for the rear? Everyone says and everyone knows that the 7 5/8ths aren't the best to handle big power, and I have to agree to an extent, but I have been reading a lot that as long as I'm not launching it all the time, and don't have slicks on it, then it should be fine. Plus side is that they're also everywhere in S10's and Blazers should I need another one haha.

But its the same as me wanting the best transmission I can get, I want some insurance in it, so I know I won't be throwing money at it for it to ultimately break. So what are my options for making my rear last, and if my options are limited, what is needed to switch to something that could handle the power that I plan on making?

I have done some messing around with Comp Cams CamQuest, and for the information that I plug into it with a cam as close as I can find for the LT4 Hotcam with 1.5 rockers .492/.492 278/287 at .50 lift, its telling me around 380hp and 450 ft/lbs.

I've heard of people on and off this site pushing stock rears to 11 and even 10 seconds in the 1/4 mile. Now I don't plan on doing any drag racing or anything with it, this is going to be a street car, and the only time I want to take it to the track is to find out what it will run when its all said and done. Thats it.

So what do you guys have to say about my situation? This build is almost two years in the making now, so I want to do it right this time around. Thanks for the help guys, I appreciate it.

 

Im still running the stock rearend with almost identical setup.

Also, my 700r4 is built with one of Dana's kits.

 

Just for fyi s10 rear an blazer rear end wont work in the f body since it doesnt have the mounting holes for the torque arm

 

I was just saying that they also have the 7 5/8ths rear, I know they don't have the torque arm...

 

I've been running that combo for many years, only about 10K miles but the trans has absolutely no problem handling the output of thet vortec/hotcam combo. No worries at all- do it.

 

I'd recommend putting on a T/A Performance, cast aluminum rear end cover in place of the stock, stamped steel rear cover, and a solid pinion spacer. Also, if your rear is an 89 or older 10 bolt, upgrading to the 90-92, 28 spline axles and carrier helps too. The 28 spline axles are stronger than the older, 26 spline axles. But yeah, on a street car where you're not doing high rpm launches with slicks, the 10 bolts hold up better than most people would think. Btw, just noticed in your sig, you have a 90 RS. If you still have the original rearend under it, it should already have the 28 spline axles/carrier.

 

I've been running almost that exact same setup for over ten years now without any issues. You'll be fine.

 

Autos aren't as hard on rear ends as manuals tend to be. At least at the drag strip.

 

If your going to go posi in the stock 10 bolt do as everyone here says...

-upgrade to 28 spline axles from a late 89-92 car
-T/A performance rear cover
-Eaton posi (yes its more expensive than an auburn but do some reading and you will see why)

Once you add up how much your going to spend to do all that make sure its worth it to you to do that instead of upgrading to a 12 bolt or a ford 9". those are both a bit overkill IMO for what you have but also are loads better than the stock 10 bolt. I have a fully rebuilt australian 9 bolt in my iroc and probably wasnt worth the money i have in it to get it where it is today.

 

If you have trouble swallowing the price of an Eaton posi carrier, another good and VERY affordable option is to grab a used, Torsen carrier from a 98-02, 4th gen rear. The Torsen is a strong unit, and since it uses helical gears for the posi action, there's no clutches to wear out. Also, they require 28 spline axles, so they'll go right along with your axle upgrade. It's fairly easy to get Torsen units on Ebay in the $100-$150 price range.