Given that both tanks were developed in the 70’s when M774 was in use, it would only make sense for these vehicles to have access to the round.
Additionally since both vehicles have similar performance they should both have the same battle rating of at least 9.3. No XM1 should be fighting 8.0 tanks like the current Chrysler model does (it is 9.0).
Meanwhile the XM1 (GM) is 9.3. this is another obnoxious example of gaijin balancing off of skewed battle stats rather than a vehicles capabilities. Of course an XM1 is going to suck if you put brand new players in it who have no idea how the game works, let alone how the higher tier modern battles work.
Since the release of the recent dev server for the upcoming patch Kings of Battle it has revealed that M735 is getting nerfed down to a sub 300 pen round when it was originally a 350~ pen round. This further gives reason to the XM1’s being given M774.
Tbf the gm gets the p suspension which is really really nice as it allows you to make yourself hull down or hide easier to kill people easier though I do agree but not just this but every vehicle stuck with m735 that’s 9.0-9.3 should be moved up to 9.3 using the equivalent because currently there’s 4 tanks in all that are using m735 and I completely feel it’s unusable at 9.3