87 K5 motor mounts

[Rob54]

Hey guys, new member here. I just picked up an 87 K5 that I’d like to LS swap with my donor truck I have parked beside it. I have read to stay away from the Dirty Dingo mounts? Also some are saying there are other mounts that can be used that work with the stock cross member? Just looking for some clarification or recommendations. Somebody mentioned “The Car Shop” I think it was but I wasn’t able to find anything.

The motor is an LM7 that I cam swapped a few years ago, it’s low miles and runs great. I plan on mating it to the 700r4 in the Blazer as the 4L60 is 2wd. This will be my first LS swap but I’ve done a few SBCs in the past. Will surely have a few questions along the way.

 

[Taylor Jay]

I am in the same boat as you I have an 86 jimmy that I am putting an Lm7 and keeping my turbo 350 trans. I am also trying to figure out if I will need to by and oil pan or a crossmember. So far what I have found is that some people are just removing the cross member and that works for them. But I am not a huge fan of that. There are also people cutting and boxing the stock crossmember. I have also seen people run and aftermarket pan and that works for them. For motor mounts I got mine off of Speedway Motors, it is just some adapter plates to run a small block mount on the LS motors and what I have read it works out well. There are people out there that like to use a sliding mount system so they can get the motor on the stock mount location and then slide it back onto the transmission. And is you are going to be running the 700R trans mission you will need and adapter to the small block toque converter to the ls engine.

 

[Wes Harden]

Welcome @Rob54 and @Taylor Jay. You've come to right place. Plenty or ls swap info here.
Those that have done it will post up.

 

[Rob54]

Thanks guys, I read some have gotten away with not having to notch the cross member and using the stock pan. I would definitely like to find out what mounts they used. If they notched, where exactly did they make the notch. Maybe some pics. I would like to use as many of my existing parts as possible to keep costs within budget.

 

[Rob54]

Anyone know about the crossmember? What if I have the 4L60E output shaft changed to 4x4? I found some mounts that say they put the ls in the stock location so i will go with those.

 

[HankScorpio]

Gen III/IV LS Swap Motor Mount and Crossmember Combo Kit for 73-91 GM/Chevy Full-Size

www.offroaddesign.com

 

[rderosier]

Anyone know about the crossmember? What if I have the 4L60E output shaft changed to 4x4? I found some mounts that say they put the ls in the stock location so i will go with those.

If you're pulling out a 700r4 the 4l60e will bolt right up to the existing transmission crossmember

 

[Rob54]

If you're pulling out a 700r4 the 4l60e will bolt right up to the existing transmission crossmember

Well then I have little reason Not to use the 4L60e. Wondering do you guys know what it takes to get the 208 to talk with the LS3 pcm? And is it possible to use stock shift linkage?

 

[rderosier]

You need a VSS provision I assume, I don't know about the 208 I went this route for the 205.

Labor to Machine Customer's NP205 Speedometer Housing for GM VSS, Tone Wheel, Plug, Speed Sensor and Pigtail Included

Labor to Machine Customer's NP205 Speedometer Housing for GM VSS, Tone Wheel, Plug, Speed Sensor and Pigtail Included Return shipping is calculated in cart. Shipping from you to us is not included. Please ship with all your contact information included and/or a copy of your order. Shipping...

www.offroaddesign.com

 

[Rob54]

You need a VSS provision I assume, I don't know about the 208 I went this route for the 205.

Labor to Machine Customer's NP205 Speedometer Housing for GM VSS, Tone Wheel, Plug, Speed Sensor and Pigtail Included

Labor to Machine Customer's NP205 Speedometer Housing for GM VSS, Tone Wheel, Plug, Speed Sensor and Pigtail Included Return shipping is calculated in cart. Shipping from you to us is not included. Please ship with all your contact information included and/or a copy of your order. Shipping...

www.offroaddesign.com

Offroad designs has an adapter with a provision which looks like a nice piece. But is the VSS for the pcm/shift points/4wd hi lo or is it for speedometer? I liked the idea of keeping my 700r4 cable driven speedometer and not needing to mess with a vss.. what did you do for your shifter??

 

[rderosier]

Offroad designs has an adapter with a provision which looks like a nice piece. But is the VSS for the pcm/shift points/4wd hi lo or is it for speedometer? I liked the idea of keeping my 700r4 cable driven speedometer and not needing to mess with a vss.. what did you do for your shifter??

You need the VSS for the transmission to know when to shift. For 4hi/4lo there is a wire to the pcm that switches the shift tables from 2wd to 4wd, I have mine on a manual switch.

 

[Rob54]

You need the VSS for the transmission to know when to shift. For 4hi/4lo there is a wire to the pcm that switches the shift tables from 2wd to 4wd, I have mine on a manual switch.

By manual switch do you mean like a toggle switch?

 

[rderosier]

By manual switch do you mean like a toggle switch?

yeah just to tell the PCM to change shift tables for 4wd

 

[Rob54]

yeah just to tell the PCM to change shift tables for 4wd

Do you remember how you wired it? I am guessing you are using the 4L60E?

 

[Rob54]

Could someone confirm if 4wd low switch is an electronic transmission thing? I will be using a 700r4 so guessing I wont need one? Pcm wont be controlling shift points unless i am missing something ..