Duane,
Before you go any further, does the Losmandy dovetail plate you now have actually fit into the clamp at the top of your GM8 head?
Losmandy has used two different size dovetail plate clamps (saddle clamps) on the GM8. The early versions use one specifically made for the GM8 which is 2.5" wide. The later GM8's came with a D-series saddle clamp which is wider. You need the right plate for the right saddle clamp.
If you have the wider plate and it will not fit into the saddle clamp on your GM8, then you need the "GM 8 UV" plate.
Also, one problem I've encountered with the Losmandy plates is that they come already drilled with many holes for mounting different types of scopes. This presents two problems when mounting a TeleVue ring;
1. You can mount it in only one place on the plate.
2. You can only put screws into two of the three holes in the bottom of the TeleVue ring.
For these reasons, I ended up making my own dovetail plates and drilling the holes where I wanted them. It was also cheaper.
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