How can you tell teh difference, with both sitting right in front of you?

 

The big one is the heavy duty unit. The paddle kit is also one big block on the hd unit. Early units used 2 seperate pieces to form one big block. Handy for gear swaps above 3:73. The regular one has a smaller paddle kit. It isn't one big rectangular block. Kind of an odd shaped thing but it is always one piece. The locking bolt essentially goes thru an eye.

 

OK, so I've got 1 HD ZT and 1 normal ZT.

Both in great shape (the HD is brand new, still in box)

Now my question is this:

I've got a turbocharged 3.1L 5 spd car. It's all kinds of fun, and the turbo doesn't hit until about 3200 rpm. Considering it's a stick, and I won't be launching under boost (boost comes in around the 60' mark):

I've got 3 3 series rear ends here, 2 are 3.42 gears (with a spare 3.42 gear set) and the other rear is a 3.23. I've completely disassembled 1 rear end, and am currently gathering all the parts to rebuild it. I'm going to stay 3.42 geared, weld the axle tubes all the way around, and use a solid pinion spacer (Ratech). All Timken bearings, and a Timken pinion seal. I'll get a rear differential stud cover from Summit later.

28splined stock axles.

I want to build a rear end that is going to last, considering it'll never really get launched on hard (maybe a 1.8-2.0 60' at BEST) and may have 1-2 passes in its lifetime on slicks.

I've got all the bearings and gear compound, etc. I'm planning on running the light formulation Shockproof Redline gear oil.

Will the normal ZT last in such a scenario? Or am I better off putting the HD ZT in? I'm just thinking I can sell the HD ZT for a decent price, wheras the normal ZT is pretty cheap.

Let me know what you guys think. I might have 350+ lbs/ft of torque total, but remember with a turbo, I won't shock the drivetrain like I would with a 383 off the line...

 

Honestly I don't think the HD ZT is much if any stronger than the std. ZT. I've heard of both blowing up. They are both better than the predecesor, the auburn posi since there are no clutches to wear.

I have the HD unit in my 98, it was allmost a $1000 at the time. I bought a regular take off one as a spare but I'm yet to use it.

What will kill it depends on how it's driven, the kind of hp laid down ect. You should be ok with 1.8 short times for a while. The weakest part of the rear is the tiny little ring and pinion. Just not enough meat there to make it strong.

Preloading the gears on launch goes a long way to saving the rear. It's a big shock when the play is taken up if they are not preloaded.