I was hauling grain in my C50 when the shifter would not move from first gear. Took the boot cover off and found that the "cap" that locks into the dogs on the side of the transmission is worn out.(Had to hold shifter handle down to finish hauling). Anyone know where I can get a "cap". Seems to be somewhat universal as it is the same as the one on my 1964 C60. Local big truck shop said part was obsolete.