S4 TII & S5 TII fuel rails interchangable?

[MaczPayne]

I've spotted a leak coming from the front side of my upper fuel rail.

Looking for replacements, does it matter if I get an S4 TII or S5 TII upper rail?

I realize the FPR's on both rails are different, but using factory High-imp injectors, would it be possible to use an S4 TII uppers with S5 TII lowers?

[classicauto]

FWIW I have S4 TII rails on my S5 TII manifolds....so dimensionally they are exactly the same. EDIT: Actually not quite, I have a couple washers under where the rails bolt on to space them up, otherwise its exactly the same :)

[RETed]

Primary rails are all the same...dimensionally.
The secondary fuel rails are different.
You can use one with spacers / washers but not vice versa.


-Ted