At this time, Sherman modelers lack a state-of-the-art 76mm M4A1. The original Italeri kit M4A1, although good for the time, definitely shows its’ age when placed next to one of the newer Tasca/Asuka kits. Tamiya released what they labeled as an M1 Super Sherman. This kit combined a new upper hull and turret with their original lower hull and suspension. Of the three major Sherman players, (Dragon, Tasca/Azuka, Tamiya) the Tamiya suspension looks to be the most crude.
What I have shown below, is a way to bring together the best components from several kits, to provide a good foundation for an early 76mm M4A1. The lower hull and suspension are from the Tasca M4A1 Late, kit 35-012. The transmission / final drive housing and early 76mm turret are from the Tasca M4A3 76mm, kit 35-19. The upper hull is from the Tamiya M1 Super Sherman, kit 35322.
Because the lower hull was welded on the later M4A1’s, the rivets have to be removed, Fig. 1. I have a few tips on the assembly of the Tasca hulls here. In order to fit under the Tamiya hull, you will need to remove about .040” off the indicated hull partitions, Fig. 2.