I don't have SM-420 experience, but have built other tramsmissions...is the cluster gear laying on the bottom of the case? I always install the cluster gears after I got the main shaft in.

Mike B smile

Mike Boteler

1956 Chevy 3100 Resto Rod
1952 Willys M38 Army Jeep
1983 Jeep CJ7 Laredo
1984 Jeep CJ7
+++++
Silver Spring, MD