Best thread I have seen in a long time! This topic is so interesting because there's very little reliable information online about the head gasket problem on the 420a. I researched for hours before doing my head gasket change and could not cross-reference good information for the life of me. Some say the bolt lengths were corrected, others say the holes were drilled deeper, some say to cut threads and some say not to, some say the problem was fixed in '97, others say '99...

Most sources I read said the problem was definitely fixed by '99. I own a '99 and the head gasket didn't go out until 176k (I read the problem would occur at around 100k if the motor had the head gasket problem. Therefore, I used a MLS gasket and the Felpro head bolts without any modification. We'll see how it goes. I figure if it lasts another 176k I should be fine since by then I'll be ready for a rebuild I suppose.

I called Mitsu. and got the head bolt measurements and they had the same lengths in their database as the Felpro head bolts in case anyone was wondering.

Thanks for the thread!