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Just thought I’d make this thread in case anyone is interested, received my cheap eBay gasket kit today and thought I’d compare my genuine gaskets to the eBay ones.
This is specifically for the SD33-series of engines (SD33 and SD33T), but the same principles apply for any engine.

This is just a warning so that people know the differences between quality oem gaskets, and cheap aftermarket ones.

Firstly the head gasket. Genuine Nissan top, eBay bottom.

First things first. The material. The top gasket is a proper MLS (multi layer steel) gasket, meaning it will seal well and take a lot of abuse.
The cheap gasket is (from my research) a fibre/asbestos gasket, similar to what was used on the early Scout SD’s, but undoubtedly with far worse quality control. These are known for blowing easily in the scouts even when using genuine pieces, an aftermarket piece will not hold up.
From what I’ve seen on eBay, you can buy aftermarket MLS gaskets, and if you absolutely cannot get a genuine one for whatever reason, try to get your hands on one that looks like the top one, do not use one that looks like the lower option.

Now, onto the actual design of the gasket itself. Look at the top photo firstly, and pay close attention to where the oil and water sealing rings are on the genuine gasket, vs the cheap gasket. Genuine gasket they’re around the oil galleries, pushrod holes and water galleries. Cheap gasket they’re around the pushrod holes and oil return holes, and bottom head bolt holes? NOT the oil feed galleries and coolant galleries. Goes to show how much research they did on these motors before slapping a gasket together 🙄. The sealing rings on the genuine gasket are also a seperate material designed to compress less than the MLS, creating a seal when torqued down. The “sealing rings” on the cheap gasket are painted on, and only on one side.

Now onto the manifold gasket.

The cheap gasket is on top here, and the genuine one is on the bottom.
I’ll start with the cheap one this time. It’s a basic aluminium laminated gasket, which in a crossflow head or one with seperate gaskets for intake/exhaust, would be fine, but since the SD33 uses one gasket for both the intake and exhaust, it needs to be made to seal even with the different expansion rates of the intake and exhaust manifold materials. This one would likely start leaking quite quickly.
The genuine gasket looks to have a similar laminated base, but has extra materials added over the ports to seal them properly. The exhaust ports have raised sealing rings around the holes so that when the gasket is compressed it seals tight against the ports, and the intake ports have what looks to be a sealant already coated on that probably works with either heat or just pressure.
From what I’ve seen, all of the aftermarket manifold gaskets are the simple laminated type. If you cannot get a genuine gasket, you can use a laminated gasket with high temperature RTV, designed for manifolds, but the longevity may be decreased.

The front main seal in the kit may be able to be used, but doesn’t look like a proper rubber seal like the genuine one. The rear main came as one piece, so I’d have to cut it in half if I decided to use it.
Preferably get these genuine, especially the rear main which is prone to leaking if it’s aftermarket.

None of the above gaskets I’ll be using for the SD33T rebuild, I got the genuine ones so I could do it right first time. The only reason I bought the eBay kit was for the rest of the simpler gaskets/seals: timing cover, sump, rocker cover, oil cooler etc. the eBay kit will work perfectly fine for these.

One day I would definitely like to get my hands on an aftermarket MLS head gasket to see how the quality compares to the genuine one, but that’s for in the future.
Nice post, yeah you can see the difference. eBay is good for some things not for others. I have a Permaseal head gasket which I believe is right up there, least I hope it is.
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