Wrong brake booster unit??

So here goes...
 
years ago before my mk2 was garaged for an age, I had to get a new brake booster unit on exchange from brake specialists.
 
I won't name names, but now im pretty peeved because the exchange unit is causing me grief. When I picked up the unit, the guy told me that there are two different yoke lengths available for the escort brake booster unit. They had knowingly given me a unit with the incorrect yoke length (didn't match up with my original one).
 
The bloke claimed it wouldn't make any difference to my brakes, but it is apparent that this claim is a big lie - I've got this extra pedal travel I have to push through before I get my brakes to engage! For obvious reasons I want to eliminate this extra pedal travel.
 
I've managed to pick up two booster units since, but the yoke coming out of the back seemed to be identical to each other. So no telling if what I've picked up is going to help me at all.
 
Some people I talk to have never heard of differing yoke lengths in the booster unit and I want to get a better idea of whats going on before I go looking further, or god forbid - seek professional assistance!
 
Is anyone here familiar with the diff yoke lengths? Any measurements out there??
 
I originally thought I could compensate for the problem by lengthening the adjustment screw between booster unit and master cylinder. But all that does is keep my master cylinder constantly engaged!
 
thanks in advance
 
Nick
 
 

thanks na.charrett! so if the whole booster and pedestal setup is different, I should be able to identify a spare booster/pedestal unit as being able to solve my woes by simply measuring the pedestal length and comparing it with the one I've got currently in the car, right?