Does anybody know where to buy the bearing carrier inside the extension box, I thought I heard somewhere that it is a truck part.

I've never heard of it being a truck part. Your best bet is to do an advanced search and search Stelling and Stellings in the Title only.
There are some old threads, but no definitive answers.
I think that Merc makes a bearing carrier/pillow block that is the same as what is in a Stelling Box. It is used on staggered Bravo set ups.
I've never seen one up close to compare though, although the pic I saw looked identical.

I took mine all out and made longer shafts.

have any pics of those mods ? or could you elaborate ?
does the bravo plug (w/original input shaft) into the bearing carrier inside the stellings box ?
i know there is a driveshaft from the flywheel but never seen how it couples inside the box

I had the same problem on a previous boat. I took the bearing carrier to a local machine shop and had them repair the carrier itself. Required some welding and machining but it worked well.

FYI - make sure you line up the carrier %100 with a bar when you re-install it. If it's out a hair you be wearing bearings out in no time.

Good luck.
Phil

The drive shaft from fly wheel to carrier then regular shaft from drive to carrier if I remember correctly. We (Brad Smith) some how got a longer shaft or sleeved add on from drive and then put HD coupler on flywheel like normal set up. Not sure if he bought the shaft or had it made. He did have to lower motors or raise boxes to line up If I remember correctly.

Many of the Stellings boxes had issues with alignment of the carrier bearing assembly. We ended up sending our boxes to Stellings who had made a jig to be able to square the surfaces where the carrier bearing mounts. No more shims and never had another issue with the carrier bearings.

The Stelling bearing carrier is a sand cast piece.
you would also need a drive flange with internal splines for the stock Bravo input shaft.
I think that an Imco one piece shaft part # 01-3549 will work ,but the engine has to be at same height as gimble.

Most people used a -1" inner transom assembly(to keep the CG low in the boat)
The only way it works(long imco style input shaft/and HD coupler) is if the box is mounted in the neutral position and you used a "0" inner transom assembly.
got lots of experience with these boxes.
I also have the last Two Stelling's carrier assembles in existence. Brand New on the shelf.
Ask Phill_p99 the "merc unit" is NOT a direct replacement.

Hey Sonic can you clear your PM box ?