MTD white roto boss 530 engine ID?

hello all,
i am new to the forum. i am looking for the size or ID of the Briggs and Stratton engine used on white roto boss 530 tiller that was given to me. i have tried with the model number and serial number but nothing about the engine comes up. I am missing some engine parts. any help would be appreciated. i can get pics if easier.
 
model 21a-400-190
serial 1I256K40324

do you know where on the engine? i cleaned off a bunch of spots but cannot see it. i plan to power wash it tomorrow to see it it becomes visible. all the videos i watch say to look on sheet metal it should be stamped but i am missing the shroud with the recoil and i believe that is where it was stamped..maybe!?