I'm convinced that GM stopped using transmission coolers because of the risk of leaks and fires caused when the trani fluid sprays on the front cast exhaust manifold that heats ot about 600* F.

The durability of the 4t65HD trani is directly related to how it is used or abused as the case may be.
Yes the heavy torque converter should be lightened by swapping in a smaller higher stall unit....like Rogue did. The stock units have been know to frag flex plates and other components during 1-2 gear shifts at 6000 rpm.
Also the differential is prone to grenading when doing one wheel burnouts. I would really recommend against one wheel spinning. The pinion shaft does not lubricate properly with trani fluid and will burn up and frag the case. That usually takes out the rest of the trani.
Highly recommended to install a limited slip differential.
Input and output shafts have splined ends that are soft and not very well hardened by heat treatment. That costs GM money so they cheap out.

So basically an Intense torque converter and LSD would go a long way in prolonging the life of a tranny? I was under the impression that a LSD would cause more grip in the tires, putting more pressure on tranny components. Where did I go wrong?

Actually many of the big dogs use stock diffs, they seem to hold up better. Once you get mad power it'* easy to spin both wheels. After a season or two on Intense Diffs they went back to Stock 4t-65 units, which seemed to last much longer, and they were still plenty able to rip quick 60'*.

FYI, th LSD is just a spring and two plates inside the stock diff, the Quafie unit is what everyone wants, but it'* much more expensive, and heavier.

ALL Automatic transmission have a tranny cooler, stock ones in most bonneville'* are encorporated into the radiator.

When I bought my 1992 Bonneville SSE come to find out the transmission had been replaced at 34,000 miles. The person that had it before me was about 80 years old. I don't know if that is normal for this Bonneville or if it is just a flaw in this car.

wow sounded like the old man got ripped off, wow thats sad. Or mabey something really did happen to it who knows...

I would lend that there was something wrong with that trans. that would have been covered under warrenty. GM really dosent like to replace trannys just because they feel like it

Yes that is true for the INTENSE type differentials because they use simple metal plates. The Quaiffes are 3 x more expensive.
That'* why I would strongly recommend using a limited slip unit like DP sells. It uses friction material bonded to the metal plates just like rearwheel drive limited slip units.
......If mine ever gets here, I will tell you more........

Really? That'* great! I've got a 94 tranny waiting around.

I'm sorry guys.... I have to laugh a little when I read through all these posts. There is a wealth of knowledge here, but I'm not yet fluent enough in car-speak to dredge through it and find a straight answer. What I really want to know are the steps I need to take to have a good, solid driveline as I gradually increase engine power with further modding. In discussing this with my buddy from the TCCOA, we're thinking I should get an aftermarket torque converter before doing a cam or valvetrain work. Does this sound right to you guys? I'm very eager to learn anything and everything I can about cars at this point, and I don't quite understand how a torque converter or limited slip will affect the rest of the transmission. Any links you guys can give me would be great. I just need to know what order I should be replacing parts on this beast. Thanks, lol. I need all the help I can get!

Well, I guess my previous post didn't generate much interest... no biggie. I've got another question though. When our transmission numbers are listed, what comprises the "transmission?" Is it strictly the gearbox, or does it include the torque converter and differential? Is this why people can replace the stock TC and run big power through everything else? If the TC is the weak link, all I need to do is get a new one to handle the added power of PEMs and a cam. Thanks for the help.