6.2/TH400 diff ratio questions

[FEF]

I'm getting close to pulling the engine out of the 'Burb and putting it in the motorhome. I'm guessing diff gear selection would be fairly critical, so I have some questions.

What's the power (torque) band for a NA 6.2?

The early 6.2s had the TH400. What gear ratio was recommended for towing in those days?

Anyone know what the combined vehicle weight (tow rig and trailer) was for something like the diesel Suburban with the TH400?

Is there a recommend RPM range for pulling 8000 lbs at about 65mph?

Some speed limits are 75 mph. I understand that I don't have to go the speed limit, but if I wanted to go 75 (without a trailer), what RPM should I shoot for.

There's got to be a sweet spot that will get torque and effenciancy. I just can't find examples from the early 80's.

Thanks in advance for the help

[chkline856.2]

First off what are you doing with the rest of the 88 burb?? I've got a Cummins 6B just waiting on a burb project!

For the fuel economy you may want to look at running an auxilary over drive like a gear vendors to help out with that. The 3spd turbo 400 is direct in top gear, and does not have a locking torque converter, so the RPMs will never be that low unless your road speed is low. With the amount of weight and air you will be pushing I would think that you would want to go with 4.10 gears if not lower. My 85 truck has 4.10 gears and seems to provide good performance. I just swapped in a 700r4 trans with overdrive and the difference is amazing. If you are really after fuel economy and don't want to spend the money on a gear vendors unit then swapping a 700r4 is another option. There is a really good post on hear about how to build them to last. Good luck with your project!