TB 9-2855-4 Arctic Top Installation on M38 tells you if the windshield shows up without wipers to simply use the wipers from the original windshield using the directions in TB 9-2855-2 Gas Heater Kit Install M38.
That would make them stock m38 wiper motors which would be Trico 63527, ORD# 7375189, WO# 674645 for original and service replacement when it is depleted would be ORD# 500844 and these are the same motors listed for the M38A1.
Cuz (AKA Wes K)
45 MB, 51 M38, 54 M37, 6? M101A1, 60 CJ5, 76 DJ5D & 47 T3-C