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Bored&Stroked · 08-01-2019, 06:09 AM

Interchange is a dangerous word here . . . more along the line that the entire GUTS of that transmission can be put into an earlier transmission - assuming that you have the correct top and shirt fork in the earlier transmission. Also, depending on the age of the case (the 33 - 39 one) and the later cluster gear, you may need to do a bit of work on the bottom of the case to clear the teeth of the later cluster gear. Not a huge deal. Also, if you're running an earlier transmission (lets say a 33), then you'll need to switch over to a later 39 style shift top - I don't believe you can use the earlier shift top and later shift (big) shift fork that the later gears need.

There are quite a few subtle differences between 33 through 39 --- so you can't easily mix-match the later parts and keep some of the earlier ones. The easiest swap is if you have a later 39 box with the larger (3" I believe) shift fork, then all the later stuff will drop in . . . and the parts can/will interchange (they are the same basic stuff). I suggest getting a copy of Mac VanPelt's transmission book - it really helps identify your options.

08-01-2019, 06:09 AM	#3
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,723	Re: Transmission interchange parts Interchange is a dangerous word here . . . more along the line that the entire GUTS of that transmission can be put into an earlier transmission - assuming that you have the correct top and shirt fork in the earlier transmission. Also, depending on the age of the case (the 33 - 39 one) and the later cluster gear, you may need to do a bit of work on the bottom of the case to clear the teeth of the later cluster gear. Not a huge deal. Also, if you're running an earlier transmission (lets say a 33), then you'll need to switch over to a later 39 style shift top - I don't believe you can use the earlier shift top and later shift (big) shift fork that the later gears need. There are quite a few subtle differences between 33 through 39 --- so you can't easily mix-match the later parts and keep some of the earlier ones. The easiest swap is if you have a later 39 box with the larger (3" I believe) shift fork, then all the later stuff will drop in . . . and the parts can/will interchange (they are the same basic stuff). I suggest getting a copy of Mac VanPelt's transmission book - it really helps identify your options.