No offense but it sounds like your breaking t-cases because you have a messed up drive line. In which case you probably will bust just about any t-case you put in there. I cracked the case on my 271 as well when my front drive shaft fubared itself.

 

it's always the front driveshaft that breaks first when my transfer case goes, but there's nothing i can do short of not having a front driveshaft in it, first time i destroyed the center ball assembly in the driveshaft, second time the very front u-joint went out and snapped the whole driveline in half, regardless the transfer case still cracked, is it the cases fault? no, but it still sucks that they break

 

Craig over at SCS, builds Quick Change type gear boxes, they sure as hell arnt streetable the use molasses like gear oil and strait cut gears. Only good for pulling or
racing. I know because i got three of them in our pulling tractors and personally know Craig Sage very well.