Re: Spring-Lock seat bushings
well it sounds like you are talking about the top bushing for the seat mount and I will tell you this, the 1.77 post with the 3/4" pin will slip inside of it easily but with very little room to move so its not loose and will not rock or wobble.
I just cut the ends off of two of these posts
Boat Seat Swivl Eze 3 4 " Pin Seat Mount 11 " Post 2114 | eBay
and stuck them inside these posts and put a screw in it to hold it to convert it over to 3/4" pin seat mount
Boat Seat Swivel Eze Snap Lock 1 77" Post Fixed Height 11" | eBay
it was a lot cheaper to do that then buy the large size bushing to fit the top of the post.
not sure if you are dealing with the same sized posts but if you are using the 3/4 pin seat base then the 3/4" seat posts fit perfectly inside the 1.77" snap lock seat posts.
if this will work for you then the standard sized 3/4" bushings (attwood sp201) are much easier and cheaper to get when they need replacing.