Question about oil level sensor and radiators

[OlGranns]

Hey guys! I just had a few quick questions about my swap. Here are some basic details to help. Its a 87 325is receiving a 98 s52 (100k miles) paired with a zf 5 speed.
1. I am switching to an electric puller fan for space reasons so my new radiator will need to have a port on the side for a coolant temp sensor. Does anyone know of a good radiator with one predrilled? And if not does anyone have a favorite cheap side radiator?

2. Some swap parts list require an oil level sensor that go with the m50 oil pan. But to the extent of my knowledge the s52 does not use one in the pan. Is this still required?

3. Will a good tightening suffice on the oil pump nut of the s52? Or is locktite a reasonable solution? Or do I need to just buy the special nut.
- Any other tips for things to do prior to dropping the engine in are welcome!

4. Will my stock 3.73LSD work well with the zf and s52? Ive heard it keeps cruising revs high but is livable.
Thanks in advance for all the help.

[mtech325]

1. I believe you should be able to use a stock late model 325i or e36 6-cylinder radiator as there is the port in the side of the radiator for a fan switch. They’re usually around 150-200 bucks for a Behr unit. You’ll probably want to convert to the late style coolant expansion tank setup as well since the 87’ car has the tank on the opposite side (passenger side).

2. The oil level sender isn’t required like you said, but the e34 m50 pan is retrofitted for it. If you get the wiring added to your harness, the benefit is that your onboard check panel will still function properly.

3. You can Loctite the nut, but the special nut was all of 8 bucks from Rallyroad.net, so may as well do it while you’re there. Some people go as far as welding the nut, but then you can’t remove it down the line. Otherwise standard refresh of simple gaskets and the rear main seal are good ideas with the engine out. AKA anything you don't want to have to do with the engine in the car!

4. A 3.73 with a ZF is going to be VERY aggressive on the highway. On stock rolling diameter you’ll be at 4k in 5th gear at 70 mph. If you want aggressive street gears, look into a 3.46 rear end, otherwise 3.15 and 3.25 are the popular street diff ratios, and they keep 80mph in 5th at around 3500 rpm.

[ian e30 318is]

1. I'm using the z3m radiator and it has a removable plug on the side similar to the e30/e36 radiators.

2. Which harness are you using? The e34 harness will have an oil level sensor plug to match the pan. The pan will need to be an e34 m50 oil pan due to sump and pick-up tube location.

3. Red Loctite and a drilled oil pump nut from Bimmerworld. Trust me when I say you don't want that nut to fall off in any situation. This is why people tack weld them on also.

4. Your freeway revs will be unbearable. I had a buddy who ran that setup and switched a month later. I would recommend a 3.46 or less.