i maybe wrong but the original street beat was pretty much a skyway TA front end with a diferent rear (platform) and 100% cromolly
the street beat you have in that picture was the very last model they did (MKII OR III) and i think it has AD mounts underneath the chain stays??
The street styler was a cheaper model if i remember and i'm sure it's not 100% cromolly?? sorry i think that was the street scene??
like i say i could be wrong though
original street beat frames are still available at reasonable prices