« Reply #1 on: May 20, 2022, 09:02:31 AM »
I had Doug Thorley Tri-Y headers in my 1991 V3500 with the 454. They fit just fine. I believe they were THY-304Y-C.
« Last Edit: May 20, 2022, 09:06:13 AM by ehjorten »
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-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6