From Rusty46's post it seems that the Main-Bolts with the M would appear to be original to the engine. I only have two of M marked bolts out of the ten necessary for my engine. Like I said earlier the only bolts which gave me trouble were the four that were marked with TR (Two stripped, One Stretched, and One was even slightly bent). The torque wrench I used is a Sears Click type wrench w/ 1/2" drive w/ a torque range of 25-250ft-lbs and now sells for ~$99.00. I have owned it for at least 15 years and I have never had it calibrated. I just read Ken's post about Torque Wrench Calibration and I now know I have not been storing my torque wrench correctly ever. After using my torque wrench I just put it back in my tool chest at what ever torque it was set at last. I never loosened the torque knob to the low setting unless I was setting it for use at that range. I live in Upstate NY and I never thought that extreme temperatures (High or Low) would effect the calibration of the torque wrench. Here in NY we do not have a problem with the hi temperatures, but we sure do have the cold temperatures. I am going to have my torque wrench calibrated and it will be interesting to see just how far it is off.
