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help guys transmission stuck in gear


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my 4 speed in my truck this morning stuck in forth gear on the way to work this is my daily driver and I need it on the road today

so if anyone can think of a fix for this our have a 4 speed laying around locally that they can part with help plz

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Sourcing another 521 4 speed will be difficult and they are 45 years old. This will give you some options when looking....


The early 620 with L16 motor and 510 wagon have the exact same 1,2,3 gears as yours. 510 4 speeds are thrown away (can't give them away) to make room for 5 speed swaps. The 510 sedan 4 speed will also work as will the one from the 710 (but not the 610 as it's too long) and the A10 with L motor. All these do not have the bolt on driveshaft flange and spline like on your 521 but it can be removed from yours and used on those. The hole in the end of the spline where the nut was needs to be plugged or transmission oil will leak out. Get a 40mm core or 'frost' plug for an engine block and hammer in.


521 bolt in spline with driveshaft flange. Remove bolt and it slides right out.IMG_0356.jpg



To use on another transmission just plug the hole where the nut was...


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that is the problem I can't find any around here closes I found was a 4 speed in sac but no way to get there now I have seen ppl taking about napz trans can I take the front part of my 4speed case and adapt it to the rear of the napz case our does my tranny come apart like that I have not looked yet


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The F4W63 (yours) has all the gears mounted in the front case. The later 71B 4 and 5 speeds, the front case slides right off and the gears are all mounted on an adapter plate that holds them. Totally different transmissions.


There are F4W63 L series and Z (NAPS) bolt patterns so if you find one make sure it's for an L series the seller may not know what he has. The NAPS 4 speed was used in the '80-'82 A10 (later 510) in the US

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