Going from memory, but I'm pretty sure this is all from canonical sources:
Blackwell was a minor parts dealer who supplied the Dragoons. I believe (but am not 100% sure on this) that the Dragoons bought shares of the firm or entered into a joint venture or something with the Marauder II.
After the 4th Succession War the Dragoons requested Outreach which was known for its Star League factories; however, it was generally assumed these factories had been stripped bare already. Hanse Davion was suspicious though, and he wanted the issue checked out. Katrina Steiner loaned him a unit that was perfectly suited to the job, the renowned LosTech prospectors and treasure hunters of Snord's Irregulars - they were sent to Outreach with orders to make sure there was nothing there that the Houses had overlooked. Seriously, that's described in the Snord's Irregulars sourcebook. ;D
Snord then flat out lied to his boss(es) and said the world was clean, while giving a truthful report to his real boss Jaime. The Dragoons then moved in and brought in their trusted buddies from Blackwell to refurbish the factories. At that point they had lost their Hephaistos space station with its ARC-2W assembly line, but kickstarted 'Mech production on Outreach in no time. I think with some SL tech even.