The X1P was an upgrade of the Stuart M3A1. During the 1970s, Brazil donated 15 units to Paraguay, which, as far as I understand, are still in service.

The modifications they usually have include M2 ​​heavy machine guns, but there is a picture of one with a 75mm M20 recoilless rifle.

The chassis was modified at the rear, as the upgrade consisted of replacing the old engine with a more powerful one.