Mercedes covered truck door variation question

[slicc64]

My later Mercedes trucks castings are missing this feature so my question is;
Is this is a regular wheel body used for a superfast model ?
I think it is because my regular wheel versions have this same detail on the door.
I am wondering if these are common?
Apologies if this has been discussed in the past but I did check both Nick's ref. and Christians and saw no mention.

[SMS88]

The red one is the post 1976 new tooling made for the 2 pack range when the original tooling wore out. The gold is very similar to RW but the casting has been changed for the different rear axle arrangement on the 1971 SF compared to 1969 RW

[slicc64]

OK thanks SMS88