Shifter pops out of gear in reverse

[Marco P Co Train]

Name's Marc.
I currently have a 71 F100 4x2 with a 302 5.0 with a 3 speed granny floor shifter I recently purchased. The truck itself is in good shape but definitely needs add'l maintenance but first things first. While in reverse the shifter pops out of gear into neutral. But if I keep enough pressure on the shifter while in reverse it will stay in gear. The previous owner used the truck for track racing and there are mods such as the steering column which is not factory original. I've already replaced multiple parts including the front brakes with a Master Brakes disc kit, dist, water pump, carb, etc. but it's just a start. Eventually I plan on replacing front suspension & the Holley 2 barrel with a 4 barrel intake n carb and possibly the engine with something more powerful. Before doing
any further repairs/upgrades I wanted to first consult with the experts. Living in the DC area it's hard locating a shop with the expertise of u gentleman. Much Respect!!!
Thanks for the add. Any advice would be appreciated

[cep62]

I'm no tranny expert , but when they pop out of gear it's probably worn bearings/ bushings.
does it make any noises like rattles or rocks rolling around in a can?

You call it a "three speed granny."
is it creeper gear first then three more speeds ?
or is it a three speed with a floor shifter ?
if it's the latter it might be the linkage out of adjustment.

[sargentrs]

Had a similar problem with my truck but it was a 3 spd on the column. Column bearings were shot and the lever spacers needed replacing. Afterwards was a bear to get the linkage adjusted right. Have you tried adjusting the levers and linkage at the transmission to insure that you're peaking out the shift into reverse? Mine also had a recurring problem with coming out of adjustment. Discovered the nut on the linkage kept backing off. Added a jam nut to it and had no more problems.