Picked this up on Craigslist yesterday, frame says super on top tube, piaggio on seat tube. Mostly 600 arabesque and in great shape! brake levers are Techtro, and left crank arm has been replaced with non arabesque. Any info you could shed on this bike would be great, just would like to know what I have not a chance I will sell it.

OHHH I love the color, I have a 84 special in blue a couple models below yours going off of group-set.
Japanese Bianchi is my guess since I'm a noob who knows very little.

The Piaggio decal and 600EX would normally indicate a circa 1981-1983, Japanese, mid-range model, typically a Limited. Yet, a top tube decal with Super could be a partial Super Leggera, which was a high end frame. However, the decals do not look look familiar and I would not have expected vertical dropouts for this era. Still, Bianchi could vary substantially, depending on the intended market. The bottom line is we need more info, specifically the info on the tubing decal and the serial number. The serial number may be in one or two parts, either on the bottom bracket or possibly both sides of the seat lug. Pics of the tubing decal would also be appreciated.

It appears to be an '81 to '83. Judging by the componts it's not an '84. The frame has lugs more simlar to Italian than Japan built . Piaggio aquired Bianchi in the early '80s, throughout the mid '80s Piaggio labeled Bianchis were varied; some Italy, others Japan built. (the models out there were all over the place as far as what was what) Some members have some degree of success in determining year and other.. by the ser. #, I find that tricky. No doubt others will give there take. It looks like my '82 but then again I've yet to nail mine down.

Gold sticker on seat tube says "Bianchi Chromo tubo rinforzati"
Serial is mu06389
Also there is chrome under the paint on the fork crown, seat and chain stays if that helps. I am leaning toward Japanese manufacture myself. Bottom bracket measures 68mm.

nice Bianchi.

Brake calipers appear to be Shimano, chain rings are 52/39 shimano

+1. 1981 based on the serial number. Japanese origin, mid-range model, but not the same manufacturer as we typically see from this era.

It rides great, weight is not bad either ~22lbs

Correction, calipers are dia-compe. I do have my eye on nos 600 arabesque calipers and levers though.