I'm Pertty sure the Alison would be easy to build. I don't have much expireance, hoever I have built a 4L80E a few times! Some major problems I had was not having the right tools! Some of the bearings require a press and it is strongly recomended that you replace a seals and bearings! Call up Hughes Trannsmissions! They are real knowlegable and if you want to do the build your self and it fails they may cover a rebuild at their cost for warrenty on their parts! They would charge for the tranny drop and instal plus labor which is a fare deal!
Also I don't know how well the Transgo is for the Allison, but it worked great for for my 4L80E on my gas! Also they sell books on how to build the trans on Amazon.com! I got one when I first built Aotu Trans!
Some advice:
1) get a book they have info like torq spec and assembly diagrams
2) They make a think gell type lube (get the Blue kind) that converts to trans oil so you don't have to change it, also, it can be used to hold parts in place
3) get a few buckets cause you HAVE TO soak clutch plates and I would recomend soaking all the parts!
4) make sure you have tones of clean space and tools organized (buy a seal pick set it's a life saver)
5) when you take it apart keep it in order from which it came apart!
6) some bearing on the pistons and drums are one way and sould NOT be lubed with the bule lube- they should be soaked in Trans oil
7) look into mods that are better than factory like no slip bearings and kevlar bands and clutch plates red Alto or Blue
8) If you have questions ask professional builders- don't hesitate!
9) Transmissions go together one way so don't force parts seals ext!
10) enjoy it it's not as hard as people make it, just a bit overwhelming for first timers!
I may have left other stuff out! Just remeber if you build it you should just replace everything you can while it's out good or not a transmission is not something to waste money on! All ask for help if you need! :thumb: Good Luck what ever you decide!
