[padresag]

how many ft. alt are you starting at. with the compression that these engs have and the light duty truck it should hold it back pretty decently descending without a jake.
what are you running for a trans.. I did have a np 5 spd. od. in mine along with a 205 t/c(ind). the 3-4 split had to great of an rpm range which made it more difficult pulling a good load uphill. there were times pulling 16,000 lbs thru the fraser canyon that at the bottom of the hill that I would just put it in second and put it on the pin at 2950 and just let her go-no temp difference, but let them lug a little and that temp climbs pretty quick. these little motors can only do so much, but used wisely will pretty well do whatever that you ask of them.
I also did have a 4core rad with eng fan and an electric backup, which worked when required
in 18 years the only thing that I had to replace was an oil cooler that leaked into the rad.
dropped the pan once to replace the pan gskt and it was the cleanest eng that I have looked into
ron