Catalyst Game Labs released several new .pdfs for Battletech.
From the release:
Experimental Tech Readout: Primitives, Volume 3 samples more of the early technology designs that dominated the universe of BattleTech during the pre-Star League Age of War period. Each design featured in this book demonstrates the primitive technology level of the first generation of BattleMechs, the last generation of Combat Vehicles (before the ’Mech supplanted them), and the low-tech aerospace units that flew above them. Although many were ultimately upgraded to “modern standards” and shown in Technical Readout: 3075, the units featured here reflect these designs as they were when first introduced to the universe they fought for. Statistics and Record Sheets are included for 14 Primitive BattleMechs, vehicles, aerospace units presented in this book, ready for play in advanced BattleTech games.