bloc
SILVER Star
I am not certain a difference was ever conclusive, just that they had different numbers. Maybe a difference in spring rate?
Did anyone ever research if the 21’ HE’s with the 3 row had the 20’ HE part number or the standard 3 row part number? That might give us confirmation that it was due to the lack of third row.
I had 2013 base and 2-row HE coils side by side to measure. 2-row is a thinner wire, but has less wraps (iirc) and the free length is longer. So without some involved calculations it would be hard to figure out the rate difference.
I never dug into 21 3-row HE part numbers to see whether they were different than late model base springs as my parts system didn’t cover that year. I’m guessing they are the same.