Good price for third member or not?

I found a cheap third member on ebay. 741 case, 2.94 gear ratio, but no posi, $150 and in good shape. I wanted to try out the 2.94 gear ratio and this whole third member is the price of a new ring and pinion set.
If I liked this gear ratio i could either have posi added or if you guys thought the 741 case wasnt strong enough for the 5.7 hemi (345-380hp and 385-404 torque), then I could start looking around for a a 489 or 742 case while continuing to drive my car with the 741 with 2.94.
Heres another question I have. I noticed on those new Yukon 489 cases it says 489 gears only. I assume that means I can only use gears for a 489 case, is this for all 489 cases or just the nodular yukon 489 cases? Also did they or do they make 2.94 gears for 489 cases or even 742 cases? I wont know for sure if the 2.94 gears are what Ill like in the end, but for the price I thought it might not hurt to give them a try.
Maybe I can use this third member for long road trips like Power Tour and later if I so desired, I could have a nice 489 or 742 case set up for local fun?
What do ya guys think?