[Bazuka]

I would like to put a 1985 1lt sierra body tub onto a 1.3lt 1987 chassis and running gear.

What issues am I likely to have?

I know the body mount studs are shorter, 35mm in the 1lt tub vs 52mm in the 1.3lt tub. Will this matter?
What about the transmission tunnel? Is there still enough room for the 5 speed without a body lift? what about position of the gearbox/T-box leavers?
I know about the brake booster but any other changes to the firewall?

I am cutting out the steel dash and making a custom one.

Thank you for your help.

[303zuke]

A 1985 shouldn't have a steel dash, it should be a plastic one.

[Bazuka]

303zuke wrote:

A 1985 shouldn't have a steel dash, it should be a plastic one.

The SJ40 1lt tub was built in April of 1985 and has/had a steel dash. I am not worried about the dash, I am going to make my own.

I am however worried about the transmission tunnel accepting the 5 speed box and the location and size of the body mount studs.

[Gwagensteve]

The inside two body studs adjacent the rear inside mounts of the seats are in a different spot on the 1.0. The 1.3 transmission will fit in the 1.0 tunnel if you have a body lift, I don't think it will without one.

I'm a bit confused about what 1.0 variant you have- but bear in mind a steel dash 1.0 has no provision for a brake booster. It's quite a hassle to fit one- the steering column/pedals are differently arranged so there's no room to fit it.

Other than that its all good. If you are prepared to fabricate a custom dash then any of this stuff is really easy to sort out.

Steve

[Bazuka]

Gwagensteve wrote:

The inside two body studs adjacent the rear inside mounts of the seats are in a different spot on the 1.0.

Hi Steve, so you are saying the only two mounts that should be different are the two most inboard of the body mounts behind the seats, the two closest to the trans tunnel? These mounts are removable as the bolt heads are not hidden by body panels, so an easy fix. The body mount studs are a lot shorter 35mm vs the 52mm of the 1.3lt body tub studs, will this be an issue? No problems with the studs under the firewall, just forward of the driver and passenger floor pans?

Gwagensteve wrote:

The 1.3 transmission will fit in the 1.0 tunnel if you have a body lift, I don't think it will without one.

I really do not want a body lift so I will have to mod the tunnel, most of it looks the same, just the front 200mm or so is a little wider... Thanks for this info as most people who have done it don't mention the trans tunnel but they all seem to do body lifts so that explains it.

Gwagensteve wrote:

I'm a bit confused about what 1.0 variant you have- but bear in mind a steel dash 1.0 has no provision for a brake booster. It's quite a hassle to fit one- the steering column/pedals are differently arranged so there's no room to fit it.

I brought a 1987 SJ51 (LWB) but the body tub was very very rusty so have found a 1985 SJ41 (LWB) tub to replace it. The id plate on the body says it was built 4/85. It had a steel dash and no brake booster. I have the peddle hardware and booster from the 87 so will fit those if I can.

[zooky08]

5 speed will fit with out body lift.

[Bazuka]

zooky08 wrote:

5 speed will fit with out body lift.

Really? Well that is the best news I have heard in ages! Why is the 5 speed tunnel bigger? just a new look?

[Gwagensteve]

No, because the 5 speed is much, much bigger than the 1.0 4 speed.

It might fit, but it might hit from time to time too. I do know it clears with a BL.

[Fatzook]

Gwagensteve wrote:

No, because the 5 speed is much, much bigger than the 1.0 4 speed.

It might fit, but it might hit from time to time too. I do know it clears with a BL.

I agree with steve.

I'd be assuming that it WON'T fit without some tunnel mods or body lift.

[zooky08]

Ive got a 5 speed in a 81 model and it clears by far

[Bazuka]

zooky08 wrote:

Ive got a 5 speed in a 81 model and it clears by far

Zooky, what does your trans tunnel look like where it meets the fire wall? Is it square or does it change to an octagon shape? Is it possible that the gearbox is mounted forward of factory? Did you do a body swap onto a later model chassis or did you change out the gearbox?

If it does fit it would be very good news but the body is off and getting rust repairs done at the moment. It would be a pity to put it back on and find out I have to mod the trans tunnel.

[zooky08]

Steve or fz may be right about modifying the tunnel but I didnt have to.
I have a g16b with 5 speed into a sj410t. Has sqaure tunnel.
Engine is deffently moved more foward then the old f10a.
I can get a pic on the weekend for you if you want.

[sideways]

The gearbox will fit without body lift or chopping, quite a few people on here have put "big case" 1l gearboxes and 1.3l boxes in without issues.

If it's actually a 1985 tub it would have the 1.3l tunnel anyway (as well as plastic dash ect).

You'l need to use the 1.3l bonnet.

[Bazuka]

Zooky, I think your 5 speed fits because it has been moved forward. The 4 and 5 speed tunnels both look pretty similar right up to the last 100mm or so.

sideways, have you done it before? These "quite a few people on here" cant tell me for sure ether way and I am still hoping someone who knows can tell me... It is actually a 1985 (4/85) model LWB sierra body and it actually does have a 4 speed trans tunnel and actually does have a steel dash.

I am using the whole 1987 front clip.

[Gwagensteve]

Who cares? It's would take an hour to fix.

Steve.

[Bazuka]

yeah I guess but the body is off and in the process of getting rust removed and the rest of the truck is in pieces. It would be nice to know so I could mod the tunnel while the body is off and before it gets painted as it will be painted off the chassis.

If no one knows then no one knows, thought someone on here would have done it though and I asked the question because it could save me a lot of time. Maybe the next time someone asks I will know.

[Bennyzarb]

Do all the body mounts line up perfectly ?

[atari4x4]

do you even read bro?

pretty sure it's even written in this thread

[Gwagensteve]

Gwagensteve wrote:

The inside two body studs adjacent the rear inside mounts of the seats are in a different spot on the 1.0. The 1.3 transmission will fit in the 1.0 tunnel if you have a body lift, I don't think it will without one.

I'm a bit confused about what 1.0 variant you have- but bear in mind a steel dash 1.0 has no provision for a brake booster. It's quite a hassle to fit one- the steering column/pedals are differently arranged so there's no room to fit it.

Other than that its all good. If you are prepared to fabricate a custom dash then any of this stuff is really easy to sort out.

Steve

[Bennyzarb]

Ahh ok soz missed that :/