You might try the schismatic for a colt SAA, as they are supposedly very similar.
No, the Stampede has a transfer bar ignition - a modern safety. Innards are therefore closer to a Ruger New Model than anything Colt ever made.
I have NOT studied how the Stampede works, however, I can guess that the spring and pin in question are used for one of two purposes:
* Drive the pawl forward as it rises. If this is the case, the spring will drive a pin FORWARD (towards the muzzle) to push the pawl forward to engage the ratchet teeth in the back of the cylinder. In a Ruger this pin goes into the primary frame from the rear, with the spring sticking out the rear. The spring is then capped with the grip frame.
* Drive the transfer bar backwards as it rises so that it clears the rear end of the firing pin on the way up. If there is no backwards pressure on the transfer bar on the way up, it will slam into the lower side of the firing pin and halt. In a Ruger this backwards pressure is via a spring-loaded pin at the rear end of the base pin. Check the Stampede's base pin: if it is "plain" at the rear then they may be using some other spring and pin to hold the transfer bar back as it rises and that might be what you have in your hand. It should use the spring to drive the pin REARWARD if this is what is going on.
I would bet you're looking at one of those two cases. Good luck!