The Navy got their TH-57s in the late 60s. But the final demise of the Army TH-67s is more due to the Navy retiring their -57s....then as mentioned politics on both sides. However I think there is a collective agreement everywhere that using a LUH as a TH borders on…fill in the blank.
As to the 505 as an option, it doesn’t meet the requirements on a number of levels. It’s the reason Bell submitted the 407GXi in the Navy trainer contract vs the 505. The ironic thing is once the Navy bids were released for public view the 407 had the lowest costs yet the Leo 119 won. I guess more politics at play.
The 407 would have been the more natural upgrade, same TC, OH-58 similarities, etc. and I think if it would have won the Navy contract, Rucker would have been a recipient of those 407 trainers as well. But time will tell. Perhaps the 72 is just a stop gap until the Army can get funding for their own trainer?