I have a 1991 honda Civic DX Hatchback with the 1.5 I4 with and automatic. The car has approximately 177k (not too bad for a honda) and no major mechanical problems except it will no longer shift into reverse. It will drive normally, shift into park and shift into all four forward gears through it's automatic transmission, but not into reverse. does anybody have any idea what may be wrong? I at first thought it was a stuck valve body but now i am having second thoughts. Low transmission fluid maybe?
Also, how much does an aftermarket or OEM transaxle for this engine/car run?

Thanks