If you're changing gearboxes especially something like auto to manual then you're into your car. So you come on here and you just have to ask someone to do it for you (ala WTB labour). Most of the guys who put their hand up will know exactly what they're doing. They'll take a weekend to do it and most likely cost less than $400 for labour.
I bought a $200 box from an XR that was being wrecked. Had to buy a $70 manual ECU from ebay and got told that a bloke on E-Series would put it in for me for $300 over a weekend. I'm not in the industry myself so it goes to show it can be done on the cheap if you shop smart

it's the best part of my job, it's amazing so many mechanics that are stumped by something so simple. most of our work with carbies comes from other workshops, to tell the truth they are worse at the "it doesn't run right" comeback.... incorrect diagnosis on their part is the biggest cause of problems