What rear ends are people using with the ls engine swaps? I am building a 5.3 right now. I don't know if I should beef up the 9 bolt or switch to a 4th gen rear?

 

stock 5.3 or even with mild bolt ons, the stock or 4th gen will be fine, getting up into bigger hp's it wouldn't hurt to upgrade 9 bolt, shoot the 4th gen rear will hold for some time until she wants to let go.

 

So either rear end is good with a little beefing up?

 

sure, it all depends on how you treat it, I've seen stock 4th gen hold 650 hp's seen the break on 400 hp's, build them right, treat them right and they can last. Its really a hit or miss. I wouldn't spend too much money it a stock unit. Run them until they break. Then build a keeper

 

^ I have seen other results. I dont think its worth spending a single dime on a stock 7.5" unit. I'd equate this approach the same as trying to marry a hooker and expect her to behave like Mrs Cleaver. You ought to know right from the start that its not if, its WHEN it breaks, because it will.

Usually they break at the worst possible moment. Plus if you are going to race the car at the track at all? Your nuts to push any power through a stock ten bolt. If it lets go at speed? You could die. Just sayin, stock diffs in these cars failing are legendary and should be considered a throw away unless your just cruising around. Any kind of race activity and they need to go.

Some guys still push them, and I admire the efforts, but I wouldnt do it. My life is worth more than a few grand to me

 

I've been pondering the same question for my LS1 swap. My reading has led me to believe
1. Don't waste on a stock 7.5" 10 bolt. By the time you buy all the stuff to beef it up and then pay someone to put it together you are almost to the cost of a aftermarket one that will eat a 10 bolt for lunch.

2. I've seen a lot of support for the 9 bolts, especially from the road racers. They only complain about parts availability.

3. I plan to use a Strange S60. Its heavier (just a few pounds) than a 9 bolt or 12 bolt but is the most efficient (Least amount of power loss). A couple extra pounds that low in the rear of the car would probably help my handling anyway.

Here are a couple links.
http://www.frrax.com/rrforum/index.php?showtopic=16176 <-talks about 9 bolts
https://www.thirdgen.org/forums/tran...range-s60.html <-one of the threads that helped me decide on the Strange S60. Be sure to read Post #7.

 

I snapped a 9 bolt pinion in two with an LB9 Iroc 5spd with GY GSC's out back on the 1-2 shift. Ive worn out a few posi's in those things as well.

But when they are tightly shimmed? They work great for road course, + Use bolt in axles.

Best posi unit I've ver run by a BIG margin was the Torsen T2R, super pricey, works brilliantly well, but dammit all if it didnt go BOOM too. Shame, loved that thing. Moser Wavetrac is the new choice du jour for a helical type carrier. Not many running them yet, but so far, so good, plus they have a transferable warranty

 

I am still using my 9 bolt but the key to its life with the 6 speed has been to not run a stick tire on it. I built it back in about 02-03 and used it with my Mickey Thompson drag radials. It worked fine with my LT1 with nitrous for years but it was through an auto. As soon as I throw them on and try to get a good track time with the 6 speed I know I will be upgrading.

 

they can live behind an automatic for a bit longer, but it's all borrowed time.

if you can't afford to upgrade now, start saving, it will be money well spent.

some of us have built our own using an 8.8 ford center section.