Hi can anyone identify this front brake that I have in my 1966 model 10 Sherpa?It works great where as the one in my 1968 model 49 not so great.The “loose one is the m49 one.The one in the bike is the mystery one?

That reminds me of a c.1966 4-spd Matador that I used to ride a long time ago, but looking for photos online I can't find anything to confirm. Looking at how the brakeplate sits outside the hub makes me wonder if the two were meant to go together.

The brake plate on the front does sit outside the hub.

The one with the cable holder on the brake plate (middle picture) is the one for a parallel hub.  Fitted up to Model 80 (and M85 Alpina) as far as I know.  This is the style below.  The actuating arm points to the rear of the machine and the cable guide is out of sight behind the fork leg.

The one in the bike looks like the later conical style hub as the cable holder has moved to the torque arm.  These were fitted from Model 91 onwards.  This is a Model 91 Front wheel.  Note the cable running to the front on the torque arm and the actuating arm pointing forwards.  Only difference I can see between the one below and the one in your post is the extra bump out on the brake plate where the shoes pivot from.  On the M91 its hidden inside the plate, your one is exposed.

Yes, I think you are right; that torque arm is like the one on my Alpina (M116) in fact and not the Matador. It has been packed away in a box for far too long now.

The one in the 10 is a bigger brake to begin with but yours is fitted with an aftermarket sammy miller brake plate with special water excluding lip! ive had a few and didnt notice much difference to a standard one. a good brake is all in the set up ,shoes have to be matched to the hub  by skimming both hub and shoes round