megatronrules:
When you're not sure, remove the old grips and make a tracing of each. Include them with your order, and you are probably safe so far as size is concerned. However most revolvers with two-piece stocks have a locating pin at the bottom of the butt, and this pin may be differently located on the Stampede vs. the Colt. When you order something intended to be used on a different make or model expect to do a little work.
Single Action revolvers in particular have close but slightly different shapes. For that reason some grip-makers request that you send the gun (or just the backstrap and trigger guard) to insure a correct fit. Others will supply slightly oversized blanks so that you can fit them yourself.