LS 5.3/Old School Manual Transmission

Pile of parts

Well-Known Member
South Jordan
Looking for advice/experience. I'm getting conflicting information online. Imagine that...🤔

Considering swaping my engine but sticking with my manual transmission - because I like it!

So, looking for experience with this topic.
Drivetrain is currently a TBI 350 with an iron Duke bellhousing to a ford T-18 out to an Atlas 4 speed. The iron Duke has the GM engine pattern and the ford transmission pattern. (Maybe I had to drill a couple of holes. I don't really remember)

The 5.3 was never offered with a manual transmission from GM but does have the spot in the crank for, what would need to be, a custom pilot bushing. I know my bellhousing will not work, due to the 5.3 starter needing to engage with 168 tooth flywheel and the 168 tooth flywheel won't fit in the iron Duke bellhousing. Advance Adapters or Novak can cover this part but I'm hoping to avoid one of the high dollar conversion kits for the flywheel, clutch disc, pressure plate, etc.

The question seems to be the shorter length of crankshaft sticking out and proper engagement of everything.

Help me with that, and I will also entertain thoughts on converting to auto. I do have the 4L60E that came with the 5.3. I'm just unsure if investing money in adapting and possibly rebuilding the 4l60 is worth it. Is it strong enough? I know the 4l80 is stronger but I would have to buy, build and adapt one.

So if you've done it, let's hear it.


Make RME Rockcrawling Again!
There were factory 6.0 trucks (same crank as a 5.3) with a GM NV4500... I don't know the details of the flywheel, but I'd look at a early 2000's GM 2500 with a 6.0 and NV4500, parts should be pretty easy to find IMO. Hell, just swap in a NV4500 and adapt it to your Atlas!

The 4L60E can be a good trans, upgraded with the right parts. 1st gear is pretty deep, plus a healthy OD for cruising around town. The sun shell is weak from the factory and the stock clutches are mediocre at best. The 4L65E and 4L70E are both upgraded factory offerings.

Summit Racing builds very affordable rebuilt 4L60E's that have some great parts, no core charge and a pretty unbeatable price. I ran the 2WD version in my El Camino and it was impressive. -

Pile of parts

Well-Known Member
South Jordan
I follow some factory, manual trucks on ig
My understanding is that manuals were offered from the factory behind the 4.8 and 6.0 but never in a truck behind the 5.3.
Fortunately, as @Greg said, all the crankshaft were the same - with exception to the '99-'00
6.0, which had a longer crankshaft flange.

Don't forget Camaros/Firebirds/Cadillac CTS-Vs were all available with a manual trans as well.
Yes, but these were considered modern manuals, built specifically for use with those engines.

I've read a lot of LS1tech and other sites. It seems simple but then I run across threads that completely make your head spin by the time you reach the end. The Questions seem to be, clutch engagement due to the shorter stick out of the crankshaft flange and also friction surface contact between the LS flywheel and old style clutch disc. Then you have metric bolts holding the pressure plate to the LS Flywheel, which may mean drilling out the pressure plate bolt holes to fit (no big deal) and also removing dowel pins from the LS Flywheel. Again, no big deal. The other part is insertion depth of the transmission input shaft, due to the shorter crankshaft stick out. They do build a pilot bushing that compensates for this.

I'm hunting down the road that @Greg mentioned. 4.8/6.0 Flywheel and finding the right combination of clutch disc and pressure plate. I'm just hoping to find someone who has done it.

I appreciate the feedback and reference to other links!
Hell, just swap in a NV4500 and adapt it to your Atlas!
Wouldn't that be nice... I was trying to keep this budget friendly.

Pile of parts

Well-Known Member
South Jordan
Sachs - Clutch Kit Part # K5552-03 from O'Reilly's
- Note *(10 Spline clutch)
Sachs - Flywheel Part # NFW1050 from O'Reilly's
LS2/LS7 Pilot Bearing Part # : 57080 from O'Reilly's
I was hoping you'd chime in. I figured you had experience with this. That seems to be the common recipie. Quick search shows K5552-01 would be the clutch kit for me, as it has the 11", 10 spline x 1 1/16 instead of 1 1/8 like the chevy transmissions.

Have you matched up that clutch disc with the flywheel? How is the contact of the friction surfaces?


Well-Known Member
Willard, UT
The disc does overhang on the inner diameter like 1"
I didn't really like it but have driven a couple and it worked perfectly.

If you want it to have full contact just use a Ram 1550X flywheel. It's a specific conversion piece made for exactly this purpose. Any old school 11 or 12" clutch will work depending on what fits in your specific bellhousing. It's around $300.