Yes, 3500_670T is basically one in the same: there may be slight improvements on the 670, but in a nutshell, yes, same engine. The long shoe can be swapped in quite easily. I think it was even a field installed update kit. We have ran across a few l's with long shoes here in KS. Really, the whole shoe is less than 6 inches longer, IMO, it is closer to 3 or 4 inches longer. We have not noticed much increase capacity-wise, surely irrigated crops would allow the long shoe to shine. We personally like the short, as it holds up better. the long tends to crack out at the rear holes more often. Also, we do not see much capacity loss, but we run a rigid and a petersen adjustable air foil chaffers in our short shoe l2's, so that may explain it. Good luck!