Yeah, 88.5 was the first year that the large pattern driveshafts were available. Some 88.5s had large, some had small.
You could also buy an 86-88 driveshaft and just swap your driveshaft ends over to them. All samurai driveshafts use the same sized ujoints, so it is an easy swap.
Oh, and all samurai driveshafts have flanges on both ends.