Does anyone know if the exhaust y-pipe is the same for a GMC 288 thru GMC 336? I’m restoring a 1958 GMC NAPCO truck back to original condition and I’m keeping the single exhaust. The left and right manifolds dump into a y-pipe that has a collector on the right where the exhaust pipe attaches. I think it’s 2” O.D. pipe. Just wondering if flange angles on Y-pipe match angles on manifolds 288-336. Waldron Exhaust has a kit for ‘57 GMC but don’t know if it will bolt to my 336? Any help appreciated. Regards, Craig
GMC did you no favors. Below is the list of GMC exhaust pipes from 55.2 (Y series), 56 (X series), 57 (T series), 58-59 (S series V8 engine serial number below 336-35000 [engine based on 58 Pontiac 370] and above 335-35001 [based on 59 Pontiac 389]). I'm assuming the "front" pipe is the Y pipe from both manifolds to the front of the muffler. Mine had been "dualed out" before I bought it in 1990.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
