When did Guild make the beige/walnut ThunderBird amps?

Hi fellows,

When did Guild start offering the beige-tolex 'Birds, with the TrailerHome faux Walnut on the sides? '65? When did they switch over to the black-tolex 'Birds? '69? Anybody remember??

My curiosity was aroused when I wound up with one with a serial number of 41xx. The speaker date codes are from early '66. Transformers are Schumachers, dated late '65/early '66. In Fender-land, the amp would have been finally assembled in early-mid '66, but I have no clue about Guild amps.

Thanks.

Check one of the Thunder 1 threads. I think matsickma had some timelines on that