does anybody know, been reading some books on 5.0l and they reckon the stock conrod bolts are the weakest link(only 5/16) and that you shouldnt rev them past 5500 is this true or just early ones

Yeah the rod and main cap bolts are pretty average and things that should really be changed for higher performance applications. A set of ARP rod bolts and main studs aren't expensive and are great insurance IMO, but you also have to look at the poor balancing of the stock bottom end and the weak stock valve springs too before you start reving it past 5500rpm on a regular basis.

so they havent changed them they reckon there not only small but poor quality, reason i ask am looking at cams and not planning on pulling the motor so no point specn cam to rev much past 5000-5500 i thought they might have upspecced in au