Shifter jumping up gears

[73chgrSE]

I have the good old slap stik shifter and ever since i got my a727 rebuilt the shifter jumps up into the next gear under sudden acceleration. For example when it's in first and you gun it, the shifter pops up into second by itself. What could be the cause of this?

Thanks for your help.

[cdr]

Broken Motor mount and or trans mount

[birdsandbees]

What ^^^^^^^ said !