Is there is a difference between 1st gen and 2nd gen 22r
timing chain gears?

 

Yes 20R and early 22R were double roller chains. in late 81 or early 82 they went to single roller chain. You can install the double roller on a 22R up to mid 84. then they changed the deck height on the block and they all had single roller chains.

 

so all the single chain gears are the same?