Bummer!
Here's some spotters and misc. info
Clutch types were last used in early 69 (the book says 68 was the last yr. for a clutch SG but some left overs were used up in early 69) and were used in 741 and 742 cases. In 69 the 489 came out and it only used a cone type SG. The 742 case went away (the 489 replaced it) but the 741 stayed and from then it used a cone type like the 489. Not saying they didn't ever use a 741 in a truck or van but I've never seen one. I've only seen 741's in cars. Unless I can get it real cheap I shy away from cone types due to them not being rebuildable and parts are hard to find. Some say their rebuildable but all you can really do is machine down the cone ends to get some more life from it, if the case isn't all chewed up which I have seen. I have also saw some that had the spider gear shaft hole in the case all wollered out and nearly everything is destroyed. Got one laying in the shed like that now.