Not that I've heard of.
Re: 'Since the stickers are long gone, I never knew what the original owner put on the bike.'
??
then...
no forest service stamp
As you say, Whatever stickers were there or not, an approved arrestor will have the 'USFS Approved' lingo stamped into the metal of the cannister.
You might try asking FmF about it. I've never gotten an answer from them ever...about anything (like a replacement arrestor for my TCII), and they have a reputation for lousy customer service..but 'ya never know 'til you ask!
There are arrestors made for some silencers:
Here!
Good luck finding something for it.
**edit**
Been looking around. There are aftermarket arrestors that will fit on a 2T silencer. Seems they don't stay on too good, though....complaint of them coming off who-knows-where.