There are just so many ranges on Puzzle #66 that its near impossible to solo.
Stats from ttdsales pool below in my sig.
Total Ranges Checked: 92,272 of 33,554,432
Total Private Keys Checked: 101.45414 Quadrillion
Percentage completed: 0.274992%
the ttd pool is using a customised vanitygen for cracking, source is available in the files on the site. seems to work quicker than Bitcrack. Worth trying out even if not with the pool, I found big improvements on the 2080 Ti's and 3070's not as much on the 3090's but still faster.
http://www.ttdsales.com/66bit/index.phpBetter to try luck alone, perhaps sharing the ranges already tested. The prize is too small to split into a group. I believe that a random approach in choosing only the intervals is the best solution because it allows you to test small portions of the entire range and make a good competition to groups organized in a pool.