Swapped in the rebuilt steering gear today. Not bad of a job.
MY source is the ebay seller; SAGINAW 7830389 POWER STEERING GEAR BOX 1978-1990 CHEVY,GMC | eBay (https://www.ebay.com/itm/SAGINAW-7830389-POWER-STEERING-GEAR-BOX-1978-1990-CHEVY-GMC/402351651872?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648)
I googled the place and called the boss. Sounded legit and very nice. I think that ebay is a safer way to buy then just sending cash and a core. Price was about the same either way .
My details are ; clamp on pitman arm
NON metric
Front steer.( they might all be front steer, I dont know. )
Cost is $350 for the rebuilt box plus a $250 core.
I found prices all over the place . Send your box and 300$ to 1200$.