There is Zoints SEO for VB 3.x which is free-
https://vborg.vbsupport.ru/showthread.php?t=127336
But I've never used it and it's been 6 years without an update. Looks to be a lot of user-provided fixes scattered throughout the thread.
I had started working on a project to bring some sort of "friendly" URLs to Vb 3.8 but I stopped because I couldn't find definitive proof it helps SEO at all. Plus at this point everyone has their 3.8 forums setup how they want, I wouldn't go changing my URLs and lose all the old content already indexed under the old URLs.