@bloc
So I finally got off my lazy rear-end.
I measure the coil thickness at 16.3mm.
I have never engaged in counting coils before and I don't have a base edition to compare against, but.... If I count the coil that touches the upper spring perch, down to where it touches the bottom perch, I count 6 turns.
The number of coils was counted by crawling under from the rear (don't have a lift). And I measured a mid coil and one close to the lower perch and they had the same diameter. Couldn't get my caliper up to the top to see if the coils tapered down in any sort of progressive manner.