[Joe K]

Define "handbrake."

Are you referring to the left handed frame mounted early "AR" pistol grip type handle.
Or the transmission front "pistol grip" handle?
Or the transmission front "pushbutton" handle?
Or the transmission side "pushbutton" handle?

None of these are exactly the same - in fact a major point of confusion in the sales of these items concerns the "pawl" used to engage the ratchet. The common complaint being "my vendor didn't send the right pawl."

The pushbutton "front" and pushbutton "side" are different in the construction of the "handle top" with the front version cast in one piece and containing the spring and the side version made up of sheet steel and bent to shape and attachment, spring applied nearer the ratchet.

Or - perhaps you're referring to the actual "emergency brake" shoes/carrier which of course is applied only to the rear wheels - and are pretty much the same differing only in placement of springs and seals.

Or perhaps you're referring to the "AR" emergency brake (Left Hand Frame attached handle) which is actually made to activate ALL FOUR WHEEL service brakes. Not too many of these survived modification to the later pattern.

Re-read: It sounds like you need instruction on the handle(s)?

Joe K