Truck Repair: opinion of best diesel engine?, cat engines, navstar

Question
hi, i have an auto shop in ny,but not much exp.with diesel,other than basic glow plug problems with few customers that own one, anyway thinking of buying a used roll off tow truck and allways thought international had the best rigs around for longevity,i'm trying to get the kind of rig that with good maint.won't kill with heavy repairs,but internationals for sale i've read seem to show a lot of as early as 100k to mid 200s with turbo and head repairs,are there any particuly strong eng. models in international or are the cat engines showing better trk records, any input appreciated thx RJ  

Answer
well this question is kinda 2 sided i like the ford line up with the super duty "but" im not impressed with navstar.after nine years of working on diesel engines cummins is the one i have had the least problems with.cummins is currently owned by ford but only comes in a dodge set up. and it is true that navstar is showing problems at 100 k. and cat is a good engine but when they brake they cost as much as 10 to 20% more to fix because of the cat logo on the box and part. i hope this info helps with your choice and good luck.thanks for the question.