When I was looking to do this , I investigated an Aux. Seat Post Mount Clamp & found Split Clamps. The old school way is to use 2 half shell clamps for the standard stock Indian generator mount. Those were running $50.oo PLUS each. So when looking for an alternative weldable top attachments for a 1 3/8" od seat post, which is pretty close to my 39 Chief frame, I found these.
Now , mind you I didn't go that route, I finally choose the C&E 12VDC unit.
But for those who are looking for say a Suzuki or Geo Metro type small alternator this may be a suitable post attachment idea.
Indian with Suzuki Alternator.
https://www.youtube.com/watch?v=psm9xD1vQ78&t=89s
https://www.ebay.com/sch/i.html?_fro...1372S&_sacat=0
https://www.amazon.com/Shaft-Collar-.../dp/B0063HNP3S
https://www.mcmaster.com/split-colla...aft-collars-9/
https://www.lawsonproducts.com/Fasteners/Collars/Two-Piece-Shaft-Collars/FS190020.lpc?&categoryId=1255&includeSubcategories =true&overrideVariantConfiguration=0&originalRoute =lawson_catalog_category_lawson&frontend-product-search-grid[_pager][_page]=1&frontend-product-search-grid[_pager][_per_page]=30&frontend-product-search-grid[_parameters][view]=__all__&frontend-product-search-grid[row-view]=gallery-view&frontend-product-search-grid[_appearance][_type]=grid&appearanceType=grid&search=&frontend-product-search-grid[_filter][tech_spec_bore_i_d_][value][0]=1-3%2F8%20%22
Now , mind you I didn't go that route, I finally choose the C&E 12VDC unit.
But for those who are looking for say a Suzuki or Geo Metro type small alternator this may be a suitable post attachment idea.
Indian with Suzuki Alternator.
https://www.youtube.com/watch?v=psm9xD1vQ78&t=89s
1-3/8" Double Split 2-PC Clamp Shaft Collar, Steel Black Oxide CCI1372S
Clamping Two-Piece Shaft Collar for
1-3/8" Diameter, Black-Oxide 1215 Carbon Steel
Clamping Two-Piece Shaft Collar for
1-3/8" Diameter, Black-Oxide 1215 Carbon Steel
https://www.ebay.com/sch/i.html?_fro...1372S&_sacat=0
https://www.amazon.com/Shaft-Collar-.../dp/B0063HNP3S
https://www.mcmaster.com/split-colla...aft-collars-9/
https://www.lawsonproducts.com/Fasteners/Collars/Two-Piece-Shaft-Collars/FS190020.lpc?&categoryId=1255&includeSubcategories =true&overrideVariantConfiguration=0&originalRoute =lawson_catalog_category_lawson&frontend-product-search-grid[_pager][_page]=1&frontend-product-search-grid[_pager][_per_page]=30&frontend-product-search-grid[_parameters][view]=__all__&frontend-product-search-grid[row-view]=gallery-view&frontend-product-search-grid[_appearance][_type]=grid&appearanceType=grid&search=&frontend-product-search-grid[_filter][tech_spec_bore_i_d_][value][0]=1-3%2F8%20%22