What is the ratio of the differential of the 1992 GMC Syclone?

if it is the same bolt pattern in a banjo housing
(fit in from the drive shaft end not salisbury type-- remove cover and pull crown wheel out from the rear) it will fit
items to consider are axle spline size and numbers and diff ratios
if the ratios are not the same , the swap will cause very early drive line failures

If the axles are from the same size vehicles the answer is PROBABLY yes.
Differential ratio can be calculated by counting the number of teeth on the crown gear and on the pinion gear. Divide the big number by the small number, that's your ratio (to 1)

the front will work, the back you can determine by counting the number of bolts holding the rear diff cover if both are the same you are good to go

yes it has to be so the transfer case doesn't blow apart

you need to fit a limited slip diff.any models by gmc that have one as std should fit,check final drive ratios first though.....

The best thing you can do is replace the gear in your rear differential to a lower ratio gear. For example if you have a 3.42 to 1 axle ratio then you should go with a 3.73 to 1 axle ratio. It will cost you a $200 to $300 if you do the work yourself and it is fairly simple. Your engine, like most japanese engines, have very little torque and a lower rear axel ratio will help but it will also limit your high end speed. You can add a high flow intake with K & N air filter and a Flowmaster exhaust for about $250, $40 and $180 respectively. They will all help but really there is only so much you can do.

As long as it's the same ratio, it shouldn't effect the computer. I would check the numbers on the rearend to make sure it is the same gear ratio. Or there maybe a problem with the replacement rear end. Is it a locking differential rearend?

yes the first 3 digits 411 is your ratio and they should be on the other rears the same way they have to match the front rear end

It has 280 hp, from the 4.3L v-6, and 350 lb of torque