Can you tell me more about the differences between 77 and 81 and the differences you prefer in 77?
Thanks!
Seconded. As an owner of '81 myself, I'd like to be able to reverse engineer '77 (and HG '79 as well).
There is this:
CT: Special Supplement 4 - The Lost Rules
http://www.drivethrurpg.com/product/148606/CTSS4-The-Lost-Rules-Special-Supplement
It is on the CT CDROM from FFE as well, but you can get it individually for $2.00 from DTRPG.
It details all of the differences between CT'77, CT'81, TTB, Starter Traveller, HG'79 and HG'80.