Hello Lionel. The 6 354 was a common conversion for most inters as well as many other trucks and buses. As far as I am aware that motor was supplied new in quite a few vehicles, as in Inters, some Bedfords, Leylands and others, both trucks and buses. The bellhousing stud patterns on many trucks are a standard pattern, numbered as in 1,2,3,4 etc so as long as you know the bellhousing number it is no problem to match them up with a gearbox. You also have a few different lengths of housings depending on input shaft length but nothing too dramatic. They are still available if you know where to look. The inters have 34inch chassis rails right from the small ones so width is usually not a problem, all the normal control cabs are the same size so a Perkins should fit in even the utes, the a,b,c,d line etc. The rear engine cross member has to be changed if original motor was a V8 as the sixes are longer. The hardest part of the conversion was always the parts like exhaust, throttle, return lines for fuel if converting from petrol to diesel, electrics etc. The Perkins Phaser motor was an incarnation of the 354 and from all accounts was not too bad. If you bought a new diesel acco at one stage this motor was supplied in the truck. A lot of bus operators used Izuzu 6BD1 motors to replace the motors in Bedford buses at one stage, but they often used the Izuzu g/box as well, although there were problems with the overdrive breaking, so this is something to keep in mind if going away from the 354, you may have to use the g/box matched to the motor you use, then you may have issues with the gearing. Also when you convert from petrol to diesel you have to think of diff ratios as well, you have to up the ratio if the diesel is slower revving than the petrol motor, although with some modern diesels the revs are higher anyway than the old Perkins and petrol motors. The only problem with a modern diesel in an old truck is usually higher horsepower = breakages if not driven correctly. Diana may chip in as she has the 4x4 inter with a jap diesel and would know how the conversion was done. I hope you get some help from this bit of info. Bruce.