Can you swap a 1996 s10 rear for a 1994 s10 rear?

If you are referring to the rear axle assembly then....

Providing both vehicles are either 2 wheel drive or 4 wheel drive I would say "yes".

The reason I made the previous statement is the 4 wheel drive rear axle has a wider track than the 2 wheel drive.

In either case, but especially in the 4WD, the gear ratiOS should match between the vehicles.

Generally speaking, a manual transmission equipped vehicle will have a different gear ratio than one equipped with an automatic transmission.

Also, if the receiving vehicle has ABS and the donor does not, you will more than likely have an indicator light come on in the instument panel.

If the opposite is the case, donor has ABS and the receiving vehicle does not then there shouldn't be any problems. You'll simply have wires that don't connect to anything if the sensor is on the rear differential.

Hope this helps.