Around 1980 was the transition year.
Some Dodge boxes will fit too.
2WD will NOT work in a stock 4WD.
BLAZER/JIMMY (full size) 80-82 Power Steering; 4x4
BLAZER/JIMMY (full size) 83-91 Power Steering
CHEVROLET 10 PICKUP 80-87 Power Steering; 4x4
CHEVROLET 20 PICKUP 80-88 Power Steering; 4x4
CHEVROLET 2500 PICKUP 89 Power Steering; VIN models "R/V", 4x4
CHEVROLET 30 PICKUP 80-88 Power Steering; 4x4
CHEVROLET 3500 PICKUP 89-91 Power Steering; VIN models "R/V", 4x4
GMC 1500 PICKUP 80-87 Power Steering; 4x4
GMC 2500 PICKUP 80-87 Power Steering; 4x4
GMC 2500 PICKUP 88-89 Power Steering; VIN models "R/V", 4x4
GMC 3500 PICKUP 80-87 Power Steering; 4x4
GMC 3500 PICKUP 88-91 Power Steering; VIN models "R/V", 4x4
SUBURBAN 10 80-88 Power Steering; 4x4
SUBURBAN 1500 80-91 Power Steering; 4x4
SUBURBAN 20 80-88 Power Steering; 4x4
SUBURBAN 2500 80-91 Power Steering; 4x4
Dodge will also work...
DODGE 100 PICKUP 80-89 Power Steering
DODGE 150 PICKUP 80-93 Power Steering
DODGE 200 PICKUP 80 Power Steering
DODGE 250 PICKUP 81-93 Power Steering
DODGE 300 PICKUP 80 Power Steering
DODGE 350 PICKUP 81-93 Power Steering
DODGE 400 PICKUP 80 Power Steering
DODGE 450 PICKUP 81 Power Steering
RAMCHARGER 80-93 Power Steering
TRAIL DUSTER 80-81 Power Steering
But the ratio is different.