The term "tanker Garand" was pure hype. WWII tankers carried pistols and submachineguns, not rifles, cut down or otherwise.
Springfield Armory did experiment with shortened M1 rifles, but for paratroop use, not tankers.
WARNING: Most of those "tanker Garands" (the Springfield Armory, Inc. models excepted) were put out at a time when M1 rifles were not being released by the Army, so they were made using receivers that had been condemned, cut in half. and sold as scrap.* Entrepreneurs bought the scrap, found parts that were usable, welded two pieces together and made "cut and weld" M1 and "tanker" rifles. Some were pretty well done, but an experienced person can almost always spot the welded together receivers either by the actual welding or by the fact that the marks on the two ends don't match (like wrong serial number for the dash part number).
*No one knew why the receivers had been scrapped - most were just worn out, but some had been burned in a fire and would have been highly dangerous if restored to firing condition.