so i have a 5.3 lsx complete motor from a 04 avalanche i know i want to hook it up to my th400 which was rebuilt last year with a 2400 stall. so my question is what kinda flex plate do i need to mate the them up. Also can i drop the engine in with the adapter plate or will i have to change the oil pan, belt set up and intake manifold?

 

You will need the accessory drive system off of an f-body LS engine along with the oil pan, pick up tube, and windage tray. You will also need a LS1/LS6 intake to keep everything under the hood. I think TCI sells a flexplate that will work with your setup, you should contact them. I too have a 5.3 LSX off of a '00 Yukon, but I think I'm going to drop in my '78 Z28. I'm currently looking for the accessory drive off of an f-body, along with the oil pan and stuff.

 

yea same here.... i was hoping not to mess with the oil pan or belt...only thing i was hoping to change was the intake manifold(which i have from a friends 98 camaro ss)

 

There are 2 styles of flexplates, flat and dished, there's also a spacer that may be needed. There's a very good thread on LS1tech, with a lot of pics that describes this, I'll see if I can find it today, As for the pand, no way, f body, vette, or winged vette will work. I used the winged vette, you can find them with oil pickup and windage tray for about $100. The alternator is too high too. There are several options to lower it.
Link, hope it helps;
http://www.ls1tech.com/forums/conver...lex-plate.html

 

would i beable to use the Power steering pump, alternator, water pump and AC from my 5.3 or does that have to be ls1 also?

 

You need to change out the cam with one that has more lift and duration to keep the flux capacitor working properly.

 

Alternator sits too high to fit under the hood, and PS pump is part of that mount assembly. WP may work but the outlet might interfere with the TB.

 

so i would have to buy a whole new accessory drive ac/ps/wp/alt then from an ls motor?
i was just doing parts check on that...and that's a bit of money.

 

You'll have to do something. Kwik performance makes nice and reasonably priced brackets. I made my own for under $100 (pic below).

 

Looks really good.

 

Just had an idea, if i were to use an ls1 intake and pick up a cowl hook can i still use the truck accessory drive?

 

I've got an L88 hood and the alternator from the truck still didnt fit.
Here you go, costs less than a cowl hood:
http://www.kwikperf.com/lsx_alt_ps.html

 

so everything else will be the same just swapping out the alt. brackets? which one do i want the fbody,corvette or truck bracket?

 

I am running the 5.3 and I did use the truck alternator/power steering bracket, but I did have to cut 3/4 inch out from between the top mounting bolt and the alternator mouting bolt. I'm using the stock hood and I have about 1/2 inch clearance. I also put on the LS2 intake and used the truck waterpump. You have to use the cable throttle control (not the electric control), and cut the extra little tab off of the throttle cable cam. I made my own motor mounts that are offset about 1&1/4 farther back than the S&P mounts. That will put the back of the motor in the same location as the original one was. No need for any modifications to the trans mount or driveshaft. For the flywheel, I extended the snout on the torque convertor about .400 inch and used the LSx flywheel. With the motor set back like this I was able to use the Corvette Batwing oilpan. It fit without interfering with the steering. I went with a 2400-2800 stall convertor. I wish I would have gone with a higher stall. These motors don't really come alive untill about 4000 rpm. By the way I am running the TH350 because thats what I had. The TH400 is an exellent tranny. I am thinking about switching to the TH200-r4 for the ease of install and the .67 overdrive. Good luck with your swap.

 

I know u used an ls2 intake but can i do it with a ls1? I picked up some engine mount brackets and am not to sure if i can move it back or not. like u did. Some one on LS1tech mention using the 5.3 flex with a spacer, is that what you were talking about?
I have a 4l60e which i picked up for $350 but i dont know anything about transmission so i dont know if its any good. and this would be my first time swaping engines...so i wanna get the engine done first then worry bout the tans.
When you cut the bracket did u need a smaller belt?

 

My engine is father forward than delberts because of my trans, that may explain why my hood was sitting on the alternator.
Mock yours up, see if the truck alternator fits.
If you go with aftermarket brackets, you can use what ever matches you water pump and crank pulley.
As delbert pointed out, forget about using an LS1 or 2 TB intake with passenger side DBW and the stock truck water pump. Do you have cable or DBW now?

 

The flywheel spacer is used with the TH400 flywheel, not the LS1 flywheel. If you already have the mounts, you may just need to make an adapter plate for the rear trans mount. Check to see how much engagement you have on the driveshaft.

 

on the truck manifold looks like DBW

 

Post a pic, if it's the big passenger side unit, your best bet is to use thr f body water pump and accessory/pulley spacing.

 

You can run the TH400 with the LS series motors. Summit hughes jegs sells the spacer and flexplates.

I ran a TH350 with my ls1 worked great with a 3000 stall (converters are cheaper)

then swap to a 418 stroker and BLEW IT TO PIECES...

now I have a TH400 good for 800 hp. not that my motor makes that much but I dont want to change the tranny again.

I would run F-body accessories or try the guys 5.3 mod above...

You can run C5 ex manifolds or better yet C5 Z06 manifolds on a budget!

LS6 intake is the best for your dollar but had to find... LS2 manifold is the same...

LS1 are free to 100 bucks... only about 10-15 rwhp difference