Spicer 212010X ended up working well. Listed dimensions are a bit off but it had some stretch and slid over the shaft on both ends easily.Id be interested in what you find out. The 261HD from my 2004 swap has the same configuration, kind of a trash design by GM. The boot on mine is bad, yours actually looks new compared to mine, lol. Part of the reason I had been thinking about swapping back in the OBS Borg Warner.
Thanks to xXxPARAGONxXx for pointing me in the direction of the Spicer catalog!