Hello all, I’m new here. I have a 2006 H3 3.5 5-speed. I bought the truck for the sole reason it was a 5-speed, but the 3.5 is just getting on my last nerve, it’s been nothing but a headache for me, but I still love the truck. I’ve several guys who have done 5.3 swaps, but none of them have utilized a stock aisin ar5. Transmission. I know the ar5 is not the strongest gear box, but this truck won’t be an off roader or street demon, and running an adapter plate would save me quite a bit of money. I really want to have a good sounding winter beater, summer cruiser. So I was hoping any of you had expertise in running a ls into to an ar5, and the direction I would have go for the engine harness, and engine computers. I’m a body technician so I’m no stranger to working on cars, but I’ll admit I’m novice is custom harnessing and programming. Thank you.

 

Is it doable? Yes
Was it done, offcourse
Is it worth it? Its up to you but it wont be cheap. I did my 5.3 to hot cammed ls3 swap and it wasnt cheap.
I would recommend you follow the colorado forums as there are many 3.5L to LS swaps documented as well as manual ls swaps.
Recently I was thinking of swapping from auto to manual, I did the research and I will post the info I got:

V8 Adapter - 500
LS flywheel - 200
Clutch kit - 200-500
Misc items such as:
Pilot bearing

now for an LS swap, its much more involved. You will need (the major parts):

V8 engine with accessories
Truck spacing accessory drive brackets
V8 engine mount adapters
H3 alpha alternator/powersteering bracket
H3 alpha powersteering pump
H3 alpha exhaust manifold
H3 alpha oil pan and oil pickup tube
LS swap wiring harness
H3 Alpha fan shroud
Custom air intake
Custom exhaust up to axle
Extended fuel line (firewall to engine fuel rail)
H3 Alpha Radiator hoses
H3 Alpha heater core hoses (or any hoses)
LS compatible Ecu
Ecu programming

A google search for H3 V8 swap will bring up some results with fully documented 3.7L to V8 swaps