Same regulator, different models..differences?

Hey all,
I am snooping around the market for a new (used , maybe) Sherwood regulator. I currently own a BRUT (SRB7100) and love it.
My plan is to get a pony bottle and hook up my current BRUT to it. I want to get a Sherwood Magnum or another BRUT to use as my regular? regulator.
I have been searching on ebay and such and found that there are later model Sherwood Magnums and BRUT's for pretty cheap. I am a poor type diver..lol
My question is what are the major differences between the older models and the newer models of Magnum and BRUT. I tried to do a search to no avail here and on Google. I dont want to buy an older model that is sub-standard even after a complete service on it.

Thanks

Did you try Sherwood's website? They have a pretty detailed description of all the regulators.
Welcome to Sherwood Scuba!

FWIW I use a Brut on my stage bottle, and have a Magnum and a Maximus as my main regs. They are very reliable, good regulators.