Help needed to decode 42RH trans number

townsend said
From the 1991 Dodge truck parts catalog.
PK 53009261 A500 with 5.2 engine , with electronic Torque Converter Lock-up used after March 6,1991. Found on Dodge pickup and vans.
Date code is July 10,1991.

Any chance you can help me decode the 42Rh below?

Thanks for your help!