Your Mercury is actually a Murray...note the "fisted" seat post tube & chain wheel...dead giveaways.The Colson is worth the effort to find the tanks for if you want one of the koolest "step thru" bikes ever built & are patient.Seems alot of kool Colsons are popping up lately...check with Nickinator...he's very keen on these bikes & if he doesn't have a tank,he may know where you can get one.You may
also want to post a "wanted" kite on the CABE.That is one of the koolest chain guards ever on the little Strato-Jet...Great finds...Congrats...Pappy 8)
P.S.-If you post the serial # on your Murray,I can probably date it for you...P 8)