In late 1979, Conn renamed their student trumpet from 16B to 18B, changing the piston design [from barrel spring to Bach style] and brace type [from telescoping to one-piece diagonal]. 
They retained the Three Marching Men bell stamp, but this is a variation I've only seen on some low brasses, late 16Es, and one very late 61B...

C. G. CONN / LTD. / U.S.A. bell logo

https://www.ebay.com/itm/CC-CONN-Trumpet-w-7c-Vincent-Bach-Mouthpiece-Hard-Case/... - serial HB010344, 344th instrument from February 1980

The red felts are also different than the usual brown they used, but they could have been changed

By comparison, https://www.ebay.com/itm/CONN-18B-TRUMPET-with-7C-MOUTHPIECE-HARD-CASE-Serial-HJ... is a standard 18B - 47th instrument from October 1980