Yes, good question. Spacers? Also before you go too far it doesn’t look like it’s mounted properly. Like it is sticking too far out from the body. There should not be a gap between the filler panel and rear body lower filler panel.

~ Phillip
1949 GMC Suburban - 10 year project
1952 Pontiac Chieftain Convertible straight 8 hydramatic
1945 GMC half ton truck - Driver- Sold 9-15-25
1946 Chevy COE - SOLD 1-5-26 BUH BYE CHEVY!
1959 GMC Half ton long bed NAPCO