The Turners on here are are possibly better at answering this one for you, Meanwhile--
The bed bars are as my green Record model, and the bed bars were solid at 1 1/2" (38mm) but i believe later versions had steel tubing. I guess solid would be better at "ironing"out any likely vibrations.
A very good starter model and mine does all I need, I bought mine about 16 years ago, has the cast iron "lid" on the drive belt access, about £200 then, from APT's Axminster original old shop.
Blue is the later colour, not sure when that came about, Record still has the cast iron quality "feel" about there stuff IMO.
Regards Rodders