LS swap for my 75

[Zoomad75]

Bruiser- We had talks about an 8.1. Fact was the engine that is in the polar bear came from my garage. My budget really wasn't jiving with the expense, harness and controller, ect. So we horse traded and I got the MEFI4 controller and custom harness to run the 5.3 on, he got the engine. Hindsight being 20/20 knowing what I've spent so far on the 5.3 the 8.1 swap might be a wash. Then again my 5.3 was a take out of a customer's truck that had us install a 5.3ho GM performance crate. So no cost out as he didn't want it. Mine has room to grow with the 5.3 though as a 6.0 isn't hard to find either.

Getting back on track, if the OP is planning on using the PCM and wiring from the donor truck, using a 208 isn't going to get the vss signal needed. Go look for a pass side drop 241 from a 90-91 Blazer or Suburban. Specifically, a 27 spline input to match the 4L60e. That will have the correct VSS tone ring and sensor on the output of the t-case to provide the input needed to the PCM. The 241 will bolt right up to the 4L60e too.

[lowrodderchev]

sweet thank you I'm going to start hunting tonight thanx again

[68Timber]

Originally Posted by Zoomad75

Getting back on track, if the OP is planning on using the PCM and wiring from the donor truck, using a 208 isn't going to get the vss signal needed. Go look for a pass side drop 241 from a 90-91 Blazer or Suburban. Specifically, a 27 spline input to match the 4L60e. That will have the correct VSS tone ring and sensor on the output of the t-case to provide the input needed to the PCM. The 241 will bolt right up to the 4L60e too.

Thanks for the correction.

[lowrodderchev]

So was pulling the harness from the motor and I'm having a hard time removing the plug that's were the shifter arm is. Theres 2 plugs neither one of them will budge. Any suggestions?

[lowrodderchev]

Its this plug

[lowrodderchev]

Looks clean no

?

[Zoomad75]

The connectors at the range switch are a little stubborn, but with a small pocket screwdriver or pick they should come free. The top connector, pull the blue clip out of the connector. Then lift up on the grey loop that is just to the left of where you pulled the blue clip from and it should release. Remember these are weatherpack connectors so the rubber gasket inside might not make the connector pop right out, you might have to work it side to side to get the gasket to release. The lower white connector just needs that bail end pulled up over the lock to release. Still, work the connector once it is loose from side to side to finally pull it out.


Heads look clean! Good Score!

[lowrodderchev]

Man I'm full of questions and a really appreciate all your guys help. So if I switch to a 241 case will I have to modify my cross member? If so what transfer case would you recommend to use to avoid modifying the cross member thanx again

[bowtieguy79]

Originally Posted by lowrodderchev

Its this plug

Attachment 1477821

A heat gun will help loosen the glue GM put in there. Works like a charm! Nice swap!

[Zoomad75]

Originally Posted by lowrodderchev

Man I'm full of questions and a really appreciate all your guys help. So if I switch to a 241 case will I have to modify my cross member? If so what transfer case would you recommend to use to avoid modifying the cross member thanx again

I'm not sure of the specifics on mounting location difference from the 205 you have to the 241. The beauty here is if it's further back on the 241 vs the 205, just move the crossmember back to adjust. Worst case, get the 241 crossmember from the same truck you got the 241 from. At most you might need to drill a couple of holes in each frame rail to either slide the old one back or fit the 241 crossmember in.

[lowrodderchev]

how does $413 for a NP241 sound? or should I keep looking? not sure what they usually go for

[Zoomad75]

Originally Posted by lowrodderchev

how does $413 for a NP241 sound? or should I keep looking? not sure what they usually go for

It's a little high, compared to the one I picked up to replace my fubar'd 241. Got mine at a local boneyard for $220 or around there. Is that one a VSS version from a 90 or 91? That's the only two years you can shoot for. Oh yeah, go 1/2 ton only too. I thought I did and the one I picked up was a 32 spline input from a 3/4 ton with a th400. We didn't notice the difference until after we put it back in and we didn't have park. Park didn't work because the 27 spline output fits just inside the ID of the 32 spline input without touching a thing.

Look on car-part.com and search for the t-case with a 91 suburban v1500 in your area. I'm sure somebody will have one. That's how I located mine.

[lowrodderchev]

Thanx I'll check them out in not having any luck around here

[lowrodderchev]

So I found a transfer case hopefully the right one the numbers,are
241c
1561 4199
116 903
272

Sound about right?

[lowrodderchev]

Thanx Zoomad75 looked up that website found a np241 for $180. It 3 hours away but a buddy of mine is heading that way for vaca so he volunteered to.pic it up so now I need a shifter and crossmember

[Zoomad75]

Good Score. Not a bad price either.

[lowrodderchev]

Got a shifter and cross member for $50 today

[lowrodderchev]

on to my next question. slip eliminator. should I get one? ive read that a NP241 with 4 inch lift and 35's aren't the best together. to much stress on the back of the case and crack it. any suggestions, horror stories, or not that big of a deal?

[Zoomad75]

Originally Posted by lowrodderchev

on to my next question. slip eliminator. should I get one? ive read that a NP241 with 4 inch lift and 35's aren't the best together. to much stress on the back of the case and crack it. any suggestions, horror stories, or not that big of a deal?

I'm not planning on running one in my 91 with the 241. Mine has the slip yoke riding in the middle of the travel at ride height so my truck with 4" of lift is not a problem. The driveline angles don't look bad either. The bigger issue is the aluminum case being fragile on the rocks, not so much the tailshaft housing. I need a skid plate more than a SYE.

Keep this in mind, most SYE's are sold for Jeeps due to the extreme shortness of their rear driveshafts. A SYE allows one to add a little bit of length and a double cardan joint to correct for the crappy driveline angles on such a short wheelbase. K5's have twice the length or better in the driveshaft compared to the average TJ/YJ/CJ Jeep. This is the main reason to add a SYE on a Jeep or anything, not to stress on the output itself.

Yes a SYE with a fixed yoke driveshaft will yield the most strength, but are you planning on extreme rock crawling? Or are you planning on trail riding with moderate obsticals?

[lowrodderchev]

Defiantly no rock crawling, a trail here and there more speed bumps that tree stumps �� the crossmember i picked up has the skid plate so i should be ok thank you

[Front Range]

Another option is a slip yoke CV if your concerned about high angle / vibration / stress.

[lowrodderchev]

found a local guy that will do my harness and PCM for $400. seem about right? he said he even has a motor on a stand for me to see it in action.

[lowrodderchev]

So finally making progress on it. Need to figure out the fuel lines. My motor has the return lines. I'm new to AN lines learning as I go. I order dirty dingo mounts, ac delco pump, and 87 tank and sender

[68Timber]

That really looks sweet. I don't speak fuel line either, whether factory or AN. I see discussions on it here and read them to try to get up to speed on the basics but I think I need the Cliff Notes or something. Keep the updates coming.

[lowrodderchev]

Brown Santa showed with gifts �� 87 tank/sending unit, and dirty dingo mounts