95 no reverse, all forward shifting OK

I have a 95 Grand Caravan. Had some fuel problems, after fuel filter was replaced and engine ran good again, I have no reverse. It is like it have 2 nuterals, no kick or anything for reverse. But all the forward gears are fine, L, 3 and OD are great. Fluid good, and did add an additive. Is there a sensor for reverse on a 6 cly 3.3L? Or could it be in the stearing collum, but reverse lights do come on. I'm 1700 miles from home and I know who ever I go to will ask for more then I can afford.

Reverse is a mannual engagement,,,,,,requires no electronics to engage,,,,more than likely,,,broken internal hard parts {gears,,or input shell} should still be drivable,,,,,other than reverse,,,,, to limp it home....that is if there is no grinding noises coming from the trans,,,if you decide to limp it home,,,,would only use "D3" or lock out OD,,,,no planitary gears required for D3,,,this will limit any more internal damage and get you through untill you can afford to fix!!!!!