Help needed with sb 318

The dipstick tube mounts in the same place for both car and truck applications... The oil pans have the same shape for the area where the stick goes into the pan at that spot, there shouldn't be a difference...
Correct about the tube mounting positions are same in the block. But there are different tube lengths depending on the body type and accessories used, and many different dipstick lengths for the different tubes as well as different pans.
For example, the longest dipstick and tube combinations were either B-vans, or maybe a motorhome chassis.
The replacement dipstick part number is an aftermarket Spectre, or something like that. Parts stores have the same crappy listings for universal fitment. Go to a junk yard and find a truck or full size B-van and you'll find a dipstick long enough.