I replaced by steering box today. It took less than an hour but I do have a lift so that certainly makes life easier.

I’ll try to make the long story short as possible. At Goodguys last month I won a drawing for a Borgeson Performance series 12.7 to 1 ratio PS box. I decided to put that new gear box in my 1984 Monte Carlo SS since it came from the factory with the F41 suspension, which includes 12.7 to 1 ratio PS box.. The SS now drives like the car was new again even though the old box was ok.

Checker is bottom of photo, 1984 SS Monte Carlo on top.

Today I put the old Monte Carlo SS 12.7 to 1 ratio PS box into my Checker. The Marathon drove like every other car back then that had 4 turns to the wheel (16 or 17 to 1 ratio). It drove with finger touch and no feel for the road. The SS steering box is identical to the Marathon box externally. It just has a better 2 1/2 turn of the wheel that gives a better feel of the road now. I also changed the intermediate shaft (also listed for the Monte Carlo) since the rag joint was getting sloppy.
As Christian Hutter stated, it’s a standard Saginaw 800 box that is on many, many cars. I do need to add though that I have forward steer,  so the application may not work for all Checkers.  In 1980 GM went to a smaller input shaft & o-rings on the steering hoses, and also a 1977 intermediate shaft is different from 1978 and newer. Still will bolt right up, you just need to change rag joint and put adapters on the hoses.

Borgeson after market box on the bottom.