Unless your commercial vehicle is a common type, or uses an engine that has continued until more recent times, such as a Morris 1000, Austin A30 or A35 where the water pump was the same as the ubiquitous Mini, then sourcing a water pump may be a problem. One avenue to look at is any links to agricultural engines. The Trojan van for example used the Perkins P3 144 engine. This started life in various garage door opener 2006 highlander of the late 1950s, the most common being the Fordson Dexta followed by the Massey Ferguson 35 which had the later uprated 152 engine.
The water pumps were near-on identical. With the popularity of vintage and classic tractors there is a plethora of spare parts for these engines, and most tractor water pumps have a kit available to refurbish them which is a lot cheaper than a complete pump. Failing this, perusing a famous auction site on the internet will throw up a multitude of water pump seals, and if the exact one is not forthcoming it may be that one of a similar size can be made to garage door opener 2006 highlander Bearings can be sourced from local bearing suppliers to complete the job.
Once the water pump has been removed from the engine, the stripping down to component parts can begin. There are no fixing pins or cotters holding the pump together, it is all done with interference fits. The first thing to remove is the fan-belt pulley, after taking off the fan garage door opener 2006 highlander This is easily removed by the use of a puller, either a general purpose type, as in this case, or the type of puller with slots through which you can fit bolts into the threaded holes in the pulley which hold the fan blade on. The contents of a rebuild kit bearing assembly, seal, impellor and a new gasket.