The stock pilot BEARING for 228, 236, 248, 256, 270 and 302 GMC six cylinder engines is a 907109. I've seen BUSHINGS used as well.
Specs are:
Inside Diameter (ID): \(0.591\) inches (\(15\) mm)
Outside Diameter (OD): \(1.378\) inches (\(35\) mm)
Width: \(0.354\) inches (\(9\) mm)
Bearing Type: Single-row angular contact ball bearing (often roller-style in historic GM applications)
Design: Typically shielded on one or both sides
These numbers are real close to MNSmith's numbers.
'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.
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