I have commissioned the manufacture of custom ARP racing-quality connecting rod bolts and nuts to fit both XPAG and XPEG engines. Original and replacement rod bolts have a limited use life, and will break when the threads begin to stretch after just a few cycles of loosening and tightening. The results of a broken rod bolt in an XPAG engine are nothing short of catastrophic, generally destroying the rod, the crank and the block. The quality of currently available rod bolts is little more than adequate. For instance, other currently-available rod bolts have cut rather than the much-preferred rolled threads found on my ARP bolts, my newly commissioned rod bolts are made of 8740 steel, and are considered bullet proof. Rod bolts made for other modern cars (MGB, Datsun, etc.) have been tried in MG engines, but the holes in the T-series rod generally require permanent enlarging to make them fit. No connecting rod modifications of any kind are necessary with my bolts, which come complete with appropriate high-tensile steel nuts. The only difference is that instead of original-style metric threads they are SAE 5/16x24.
A complete set of eight supremely- strong and reliable ARP rod bolts with nuts is $250 including priority shipping.
This is a cautionary photograph of what
happens when a rod bolt comes loose!
(In this case a Nylok nut from the usual supplier)
(Photo courtesy of Bruce Cunha)