The only differences on the LTD are: solid pine cabinet, lacquered tweed, Jensen speakers (Emi's in the older ones), has a bias pot, and tube rectifier stock. Otherwise the circuit is the same and from my experience the tonal difference is relatively negligible. The only thing that can't be done to the pre-LTD's to make them identical is the cabinet (well, unless you have one built), but you can easily lacquer the tweed (Minwax Polyshades works well), add a bias pot, and put in a tube recitifier in place of the stock SS one. And speaker wise many prefer the older blue frame Eminence speakers in the pre-LTD's anyway, but many speaker vendors sell replacements if you want to change them out.
That's right. I had an old one for several years. I laquered it (a fun Sunday project) and put in a tube rectifier. My tech set bias when it needed tubes. But that was once in what, two years? A couple friends have the newer ones. I haven't followed the pricing, but it would be interesting to know what the used prices are for the two models. If it's much more than $75 it wouldn't be worth it to me. Oh, speakers -- I liked both the blue framed Eminence old ones -- which are darker -- as well as the Jensens in the new ones. The Jensens are a little more complex sounding; would probably take them if all else was equal.