The Grizzly I was a Canadian-built M4A1 Sherman tank with relatively minor modifications, primarily to stowage and pioneer tool location and adding accommodations for a Number 19 radio set.

After the war, a number of Grizzly tanks were sold to Portugal as part of the NATO military assistance program; they were retired in the 1980s.

After the fall of France, it was decided the nascent Canadian armoured divisions would be equipped by tanks produced in Canada.

The Sexton Mk II used the Grizzly chassis, with the upper hull modified to carry the Commonwealth standard QF 25 pounder gun.

Some Grizzly medium tanks were fitted with an Ordnance QF 17-pounder (as per the Sherman Firefly) and used for training in Canada.