Evan is right on here but it's wise to adjust the worn & floppy shift linkage before touching the tranny . put the gear lever in the cab @ 3:00 and wedge it there as it'll droop on it's own , now go look under the hood at the two little levers on the steering column ~ they should be paralell , if not you'll beed to take the shift box apart and scrape out all the old , rock hard grease and shim & adjust , re-lube with good chassis grease (white Lithium grease is best here) , and then replace the bushings where the rods go through the arms as once those bushings are shot , poor shifting results . use PVC or whatever you can find , I dunno if the re-pop bushings are any good , hard plastic is best , the original ones were soft rubber to be quieter , not a good plan . I've seen very good homemade aluminum ones too .
Next , go underneath the truck (parking brake set and wheels _chocked_ !) with the tranny in neutral , remove the little cotter pins holding the levers to the tranny arms and shim them up using thin flat washers untill the pins just fit snugly on the arms , no droop but NO drag either , then adjust the pins so they fit in the holes on the arms dead center when the shift lever is dead nutz @ 3:00 ~ this will " time " the linkage and usually correct 90 % of
poor shifting .
To recap : remove all play and floppyness in the shifter rods then lube & adjust .
Drain and re-fill the tranny with 90W gear oil or 85W-90 if that's what your FLAPS has , remove the fill plug BEFORE you drain it and re-fill to the edge of the filler hole , truck on a level surface ~ this is very important ! these old trannies leak no matter what and should be topped up at least 2X / year regardless of miles travelled .
-Nate
