I know they had one break, also had a problem with the weld on Borgeson unit because you cant take them apart to rebuild them, so when you weld it on the grease cooks out of it some what then you get premature wear from lack of grease. the flaming river unit you can take them apart and rebuild them so when you weld it on you take the half you need to weld and weld it on and let it cool down then put it back together.
he also said the borgeson is plain steel and will rust, you have to paint it. flaming river is nickle plated. they also have a all stainless one too. I talked to him a bit ago about one for 67-72 application. he said you use two universal joints and the shaft inbetween the universals. they also make slip shaft, shafts too. he said in the nickle plated units he would change the steel set screws out to SS also.
hope this helps