When you say it always sat on it's back rollers, have you compared to a Challenger in the field, and did the 8370 you tried sit on it's back rollers?I had a 8345rt and as said it always seemed to be sat on its back rollers,
Very nice to drive with better draft control than the challenger, but I would not have a Ivt, personally I'd look at the the E23, a demo 8370rt I had it in and it was a awesome.
The one I have looked at has extra weights at the side of the engine at the back of the Radiator, quite a few of the ones I have seen have them fitted.It had front idler weights and JD pack front weight. Not seen a JD with track weights like the challengers have tbh
Funny but my experience is the total opposite. Had a 765c the hardest thing to pull was the twin leg mole. It never really happened. First off we tried a 800 front weight pack but that didn't really help, so brought more idlers 16 total which was better. It always sat back when pulling hard then it would go off track and start to spin trying to get back on line. Changed it for a 8370rt which has a longer track and seems to sit level and wether being cvt it controls the power a lot more and so seems to pull the mole almost effortlessly. As for turning on the ends no real difference I find.Personally from my experience no. JD always sit back on rear idler when on real heavy draft no matter what weight is on front as can’t properly ballast the track frame like a challenger! I’ve had more experience with bigger ones (MT865+) but no twin tracks are great when turning wouldn’t say much in it. When trialling a 775 with full track frame weights and 16 idler weights pulled level at all times and turned best I’ve seen from a twin track level and without to much scuffing. But speed and operator have more to do with it!