I'm not sure which part number my aluminum MP hemi heads are, but they've served me well. They were new sometime around 2004-2005.
The guides are soft, but other than that I've had no problems w/ them. Been running them since 2006.
The casting on mine is 2531110-M
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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