Military fitted 12j?

Hi guys, I have bought an ex military series 3 88 truck cab (pickup) which I believe was built in 1978 and released from the military in 1991.... It has a 12j 2.5 na engine fitted which the previous owner believed was fitted by the military; the hand throttle works and there is a set of dual batteries in the box between the seats.
The vehicle has a Q plate and appears to have been a kind of recon vehicle with a map light, ,'beacon' button, convoy / s convoy switch selectors on the panel which operates the headlights, it also has a box with a series of switches attached to the rear tub between the seats in the cab.

It also however has signs of buying rebuilt at some point with the roof inside the cab a different colour to other panels etc and a 'stack pipe' exhaust fitted through the rear tub.

Did the military ever fit 2.5na engines to series vehicles? Or is this likely a re-built vehicle containing some military parts?

With regard to the exhaust, I intent to re-route it back to a more conventional position, would a 2.25 diesel system be compatible with the 2.5 engine?

Cheers in advance guys, thus is all very confusing! Hamish

Yep, standard engine. I don't know if a 2.25 exhaust will fit but if the bore is smaller on the 2.25 exhaust don't use it.
The 2.5 doesn't need any performance down grades.
On cobblers...
Just read the post again, S3 not ninety. Doh!
Ignore the above

i doubt the military would fit a stack exhaust. post de-mob engine change i reckon

I've always assumed the 2.5 came out with the 90/110 , it was a common upgrade much like sticking 200tdi in 2.5 and TD models.

Back to the exhaust, if the bore size is similar then mating a 2.5 down pipe to a 2.25 system should be easy enough if you are handy.

Cheers guys that's shed some light onto the issue, if it was released in 91 is it possible that the engine change occurred whilst with the military from spares they had for 90's? After their sympathetic driving blew the 2.25 up....! With the stack pipe being a later modification (done v badly) by a previous owner.

Do you think it would be easier to try and source a 2.5 exhaust system and make it fit the vehicle? Or make a 2.25 system off of paddocks mate with the engine?

Cheers, this is really helpful

I'm unsure of the exhaust route between a S3 and a 90, a 90 has different rear suspension so may fowl on a series.
Easiest is mate a S3 to a Nad downpipe. Get a s3 complete system including down pipe and a new 2.5 downpipe only. You should then be able to fit the system and see where is best to make the join.
I suspect splicing the front of the Nad downpipe to the rear of the s3 downpipe is the way to go. Keeps the rest of the system standard and easily replaceable in the future.

Flossie that's an ace idea re keeping everything replaceable, i shall Have a browse on tinternet for the single nad pipe. It will be good to restore the exhaust to its original position and make the rear actually usable.
Cheers for all the help

Don't forget, the military Ninety (not 90), is a hybrid mix of Series 3 and civilian build Ninety parts. Supposedly so that REME could use common parts on the older and newer Landys.

I've had problems fitting aftermarket exhaust components (second silencer and final tailpipe) from different suppliers, as the crafty manufacturers haven't followed Land Rover's pattern, so that tubes from different manufacturers won't mate up ! As the suppliers of these parts use original part numbers, it's impossible to know if a new part will fit if you're not replacing both parts. You then need an adapter.

Exhaust converters/adapters - to connect differing fitting or different diameter pipes - are readily available on the Internet.

Have fun
Rick