my 1988 xr4x4 2.8 smokes a little more than it should and it stinks i was told by the prev owner that it was running on unleaded but im not to sure how can i tell if its been converted i tried looking for the stamp marks but cannot find them proberley looking in the wrong place is there any other way of telling.

 

Due to age it can run unleaded with no mods, but not LPG, it's a myth that unleaded can run LPG perfect, unless you drive like a old granny!!
I ran mine on unleaded until I LPG'd it best thing I ever did, I had dry fuel seats fitted, much much better on gas than petrol power wise, presumably due to piss poor head design.
tabetha

 

so it can run on unleaded even tho it might be leaded heads still fitted.

 

As far as i know the only factory unleaded 2.8 cologne was the efi version in the granny 4X4 ?
here's what and where anyhoo let us know what the result is i like to keep track

 

All I can say is I had mine for 3 years, ragged the arse off it, as was so slow, despite brand new rebuild(and modded) on 2 years unleaded fuel over more than 30-35,000 miles, never a problem, the head material is very very hard anyway, but then went to LPG, got more power and torque, but needed dry fuel inserts as it ate the head away!!
tabetha