1948 3100- Need direction on 5.3 year and 6l80e or 4l60e

[uhcoog1]

Trying to decide on a motor and transmission for a 1948 Chevy 3100 project. I know very little about gen 3 vs 4 motors, and I know even less about 4l60e vs 4l80e vs 6l80e.

My preference would be to pick up a pullout 2008-2014 truck 5.3 with 6l80e and run it bone stock.

Will the trans fit okay under the 3100? Is a 4l60e significantly smaller?

I see PSI conversion sells a harness, but they don't sell a 'kit', so possibly I need to source an ECU and pedal? Are the gen 4 motors hard to run stand-alone?

We're using the stock frame with speedway motors suspension front and rear.

Thanks fellas

[mongocanfly]

welcome...
when you find your engine make sure it comes with the ecm and gas pedal and all accessories...4l60 is basically a 700r4 and a 4l80 is basically a th400 with od.....I would find a engine trans combo and go with it as a complete unit...regardless of which trans is there...not sure what you mean by psi not selling a kit...I've used them and they have quality harnesses....with the right parts they will all run....don't pass up on the earlier yr model LS engine combos...plenty good enough and seem to last many many miles...and would save you some $$$
depending on how you set it up expect to do floorboard mods.....

[uhcoog1]

Thanks for the reply

How much bigger is the 6L80e vs the other two?

[mongocanfly]

not sure on diameter differences but the 80s are bigger ...heres this

[Dan in Pasadena]

Just commenting to offer another opinion:

When I took my ‘55.2 to have IFS installed the guy I used - who has done MANY LS swaps - asked about what engine I would be using? I told him I had a 283 with camel hump heads that was over cammed and had a weak cylinder so it would need some work. We discussed rebuild costs and a 350 engine vs. an LS swap and I immediately thought about a 4.8 or 5.3 swap.

His comment was that I would be “very happy” with either but they would lack, “...follow on power”. I said, What’s that? He said after a year or two I’d tell him the engine/trans combo was perfect but I’d wish it had a little more power! At that point his counsel was that it would cost more to increase power very much on a 5.3 (& corresponding upgrades to the 4l60e) than if I just went with a 6.0/4l80e to begin with.

After considering the small additional amount for an LQ4 (6.0) vs 5.3 I went with his suggestion. My engine/trans came out of a wrecked Isuzu N series delivery truck that had 81,000 miles. Because it was a delivery vehicle it came with a slightly stronger 4l85e trans. Even though factory hone marks were still visible in the cylinders, we installed new rings, main, rod and cam bearings.

I’ve only driven mine around the block because at the time it still lacked windows, bed and hood but I couldn’t resist stepping on it and it runs FANTASTIC. I’m sure I’d have been very happy with either the 4.8 or 5.3 for my original post-retirement, daily driver plan. But now it’ll be more fun!

[mongocanfly]

prices for 6.0s around here have gone crazy...they used to only be a little more than a 5.3 but now they ask nearly 3x or more than what a 5.3 will bring....
good suggestion to look at a delivery truck though...

[CountofMonteCarlo84]

I like my LS1 with 4L60E

[Speedbumpauto]

I did the 4L80 after trying a 400 with a manual OD. Since I'm spending your money I'll relate; Shortly after my purchase but before the install in the 55, I fulfilled a bucket list thing and got a C6 Vette with a 6 speed auto. When I was shopping, I didn't give much thought to the year split when the vette went from 4 to 6 in the auto. It was more of a budget thing. Had the vette for a couple of years now and the grin that 6 speed puts on my face is "priceless." And that's in a light car with lots of engine. Just some food for your thoughts and wallet.