Would suggest you start by removing the wiper arms from the splines on the outside of the cab. (See the 2 screenshot pictures attached below for reference in the next steps.)
With that done, manually move the wiper motor arm to the 12 - 6 O'clock alignment position (arms disconnected from motor).
Next, position the L and R wiper arms so the short arm on each splined drive shaft on both sides is positioned at 6 O'clock (actuating arms still disconnected).
Once these 2 steps are done, your "short" actuating arm for drivers side should reach the lower pivot point on the motor arm and the "long" actuating arm for the passenger side should reach the upper pivot point on the motor arm.
If they do, attach the two activating arms and reinstall your wipers to the splined shafts in the 12 O'clock position and things should all connect and your alignment process should be successful.
If the activating arms don't reach from the motor pivots to the splined drive tabs, there is either damage to one or more of them or you possible have some incorrect parts involved.
Check back and let us know if this is helpful and you figured it out (or not) please.
Dan
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
