Can I put a 1968 style water pump on a 1973 engine. Both 318’s.

Here’s my dilemma.

My 1968 D200 had a newer motor swapped in. I then swapped in a 197X 318 from my 73 D100.

The radiator currently in my 68 is of unknown condition. It is assumed bad. Visual inspection shows cores partially blocked, some completely. It will need rodded out, but the issue is how long it sat (decade plus) with water in it, and it is of unknown origin. It was hacked to get it to fit.

The top hose is on the drivers side, bottom hose is on the passenger side. The original radiator would have had a top hose in the middle, and the lower hose on the drivers side.

I want to put an original style radiator in it. To do so, means I will need the water pump with the lower hose outlet on the drivers side.

So, what do I have to do to put a 68 style water pump on the 70’s motor?

I know the newer one is aluminum and the old one is cast iron. Timing marks are on opposite sides.

I don’t have power steering though it is a power steering assist truck. I would only be running the alternator. Are the alternator brackets the same?

Sorry for so many questions. I am on a time crunch to get this done, so any and all help is appreciated. Thank you!

You should be fine with a 68 water pump on a later engine. RockAuto shows the same gasket for both pumps.

I have never done it, but as I recall to get everything correct, the timing cover housing has to be switched over as well. but I could be wrong on that. I may be thinking magnum to la stuff.

You can keep the tcover that is on there & with the marks being on the dr side you have to aim the light just right to see em with the cast iron early pump cuz the hose is almost in the way & it is a pain & it is way easier to source a bolt on tab (FABO has em regularly) to get the marks on the pass side & remark the dampener & finding true TDC or since you are in a time crunch find true TDC & add a homemade pointer on the pass side & mark the dampener at TDC on the pass side to match your pointer. the cast iron early pump is much shorter than the later alum one so a pulley swap will be needed (a pain). Just me (if possible) I'd get a rad with a pass lower neck & keep you current setup. The pump to tcover gasket fits better one way so flip it dry back & forth & you will see where one way covers the sealing surfaces much better

Ok so it sounds like it’ll physically bolt on.

I have a plethora of pullies to pilfer, so I may have one that works.

But what about the alternator bracket? Will it bolt onto and into the same spot? Is it a different bracket altogether?

Thanks guys!

All the pulley's will be different, and the alternator mounts might not work too. The later style aluminum pump is thicker so the pulley's are deeper for everything to align...

& going with the early pump you will need to go with shorter bolts to maintain the original amt of thread engagement.

In a nutshell all of the pulleys and brackets have different offsets...As previously mentioned you'll need the shorter water pump bolts...but everybody forgets the difference in the size of the bypass hose...Cast w/p is smaller by a bunch...

New pulleys...alternator brackets and spacers...bypass hose and a belt should be all that's needed.

The pulleys you need will be from the earliest 318 poly motors up through the 273-318 and 340 until 69... Staying away from any A/C equipped cars...

In case you don't have it, this is a bolt-length reference for the early water pump...

- EM

^^^ EM thank you EDIT 1&3/8" of shank on the bottom (2) bolts. I ain't checked the rest.