It is all about how much $ ya want to spend. More $=better trans. I have been where your at. Done rebuilds and been happy with em but I also ran power adders. I recommend gauges like edge insight and custom EFI tuning. Also get best trans ya can afford but don't tune it without a solid above stock level trans. Converter upgrade is required!! Don't skimp on this. Research cummins forums for tons of info on this. Firepunk any level is great idea. Trans shops can build em as well BUT do homework and give em list of upgrades and what parts/brands are going into it. Single disk quality billet converter, deep pan, valve body, gm solenoids, strut, 2nd gear etc, bands. Triple converter or input isn't really needed unless ya plan on rodding her hard. Like 500hp, custom turbos, racing etc. IMOP. I have 06 5.9. No emmisions, some intake upgrades EFI tuned, Valair 650hp organic clutch 6sp. Great trucks. Fuel filter upgrade, delete, air filter and tune it with gauges. All the power you will need and a big change from stock levels. Safe good power of 400hp and 750-850tq towing reasonable loads. Biggest mistake a guy can make with 48re trans is to throw box tune edge and rock it. Trans will go soon. 176k is good and proves you didn't beat on it. Anarchy diesel Phil is where I got my EFI tuning.