saddle tanks

[Fish & Chips]

Does anyone have any information or specs on the original saddle tanks that were installed in the 1976 model year?
I bought my V about a year and a half ago and the 12 gallon plastic tank range is getting old!!!
Any help will be greatly appreciated.
If anyone knows of a local shop that has done this work for them, please share as well. (Southeastern Massachusetts )

Thank you in advance