Help me please, how can I tell if my 91 Buick Regal has ABS in the back, I never received an owners manual for

There are three main ways to check

First see if there is an ABS light on your dash when you turn your key to the on position. If there is no ABS light you do not have ABS anywhere.

Second take the rotor off and see if there is a gear around where the rotor slides onto the spindle. The gear will be what the ABS sensor uses to sense when the wheel locks up.

The third is to see if there is a black round sensor that points towards your rotor behind the rotor usually mounted about one inch from the backside of the rotor.

If it has ABS, it will be on all four wheels. Pickups had rear ABS for a few years, but not cars.

Just my guess, but a 91 Regal likely doesn't have ABS. See if there are any wires/harnesses going to the brake assembly. That would be one indicator.

I had a 92 and it said it had ABS on a plate on the dash to the left of the wheel.

If you would like a manual you can buy one from a local auto parts store and it will show you lots about your car and ways to repair it.

Naw it dont got it too early a year model