I’m pretty sure the 4:20 rear ends are really 4:10 gearing front and rear (or they are 538 gears). What’s a 538 GM transmission? There’s some mixed up numbers. The trailer certainly is interesting.
“1942 Willys Jeep/With Trailer, 1967 Ford Motor-225 odd fire, 420 Rear Ends, 538 GM Transmission
PowerLock Front&Rear 8000lb, Warren Winch, SoftTop with Doors, Asking 7200.00 530-333-1661”