few years back, when i went on hunt for TLB and ended up with the ford 555c. i went by a good amount of places that had buckets. but the companies really did not have an internet website or listed anything on there websites. you might try hitting machinerytrader website and see if you can dig up some nearby companies and giving a few calls around. *shrugs* you might come up with something.
we all have issues with dirt / mud getting stuck in bucket from FEL to backhoe / excavator buckets. i have seen a few variations (never used them) from holes in back side, to holes in the sides near the back. i have also seen some sort of hydrualic "punch" for lack of better words. that pushed the dirt from back of the bucket out. the bucket was kinda like a cylinder, and the back was like the piston of a hydraulic cylinder pushing sticky mud out.
--the backhoe bucket i have does have rear hole in it. and it has saved me a few times from suction holding dirt/mud in bucket. i am not sure if everything gets a little "edgy" for hole in bucket thing a little spilled dirt is going to ruin your day or what. maybe dealing with pea gravel to 1" gravel for say flower beds around house or driveway. but for just general dirt? *looks confused*
another issue with buckets at least for me is "side scraping" of the trench, i either hit a larger rock only partially sticking into trench, or run into a tree root or like. it is easy enough to knock the rock / root off to the side with the bucket and rip the roots out or cut the root. but being able to toss on some sort of side scrappers i would love to have them. never used them. but there been times were i had to take out a larger area via digging to deal with a root / rock. if i could bolt on a couple side scrappers i would imagine things would of went easier. even with down time of messing with bolts for side scrapers and getting wrenchs and like around to do it. then take them off. just being able to put a little "notch" into the trench so i could slip the pipe around the rock / root would have made my day much easier. and then dealing with filling everything back in.
i would prefer "bolt on" teeth on backhoe bucket. to help scrap bottom of the trench to clean the bottom of trench out better. teeth just seem to make a bigger mess for me. and trying to use bottom side of bucket can bet a tad tedious at times to compact the dirt in the bottom of trench before pipe goes in. on other hand, i most likely require teeth. trying to dig in to a few places here on farm. and about only way i got through the first few inches of hard compacted dry clay was due to the teeth on the backhoe bucket.
google keywords...
backhoe trencher bucket
Trenching Bucket Fang for Excavator Mini or Backhoe | eBay flipping through pictures the bottom of a couple of them *cringes* i like compacting dirt with bottom side of bucket. and some these buckets had an upside down U shape to them... huh?
TRENCHER FANG same as above
Railroad Cribbing Buckets for Loader Backhoe and Hydraulic Excavator -- Dymax Attachments
Trenching Buckets – Insightful Notions One Should Know | Il Zacatecanos like overall shape more of a J shape. meaning does not matter what angle i have bucket i am sure to make contact with bottom of bucket and bottom of trench to compact stuff.
12" backhoe bucket | no-reserve auction on Thursday, February 28, 2013 | re-inforced sides? be nice if it was sharpened down for side scraping.
http://www.craigattachments.com/exbmass/ standard D shape bucket. not really impressed with. you see them everyone in advertisements. the buckets work but...
http://digrite.com.au/300mm-trenching-bucket-adaptor-teeth-4-6t-excavator-d307/ bucket looks like a nightmare to get mud/dirt to clean out of it when you go to dump the bucket due to how deep it is.
http://digrite.com.au/300mm-trenching-bucket-with-flat-teeth-4-6t-excavator-d268/ to much L shape to it. look to be a nightmare to use back side of bucket to compact dirt with. flat bottom really? maybe bucket used for something else or just simply have not used it and not understanding it.
http://www.ebay.com/bhp/12-backhoe-bucket looks like it ready to take on some side scrapers.
i noticed skidsteer buckets for trenching tend to be a longer J shape like bucket.