I replaced the gauges in my TR6 with Autometer gauges, so perhaps my experience will be helpful for a TR4.
Speedo: The cable fitting on the back of the mechanical speedo doesn't match the Triumph cable, so you will need an adapter if you use the mechanical speedo. There is a company that specializes in adapters to match gear ratios, so they should be able to make one for you (I still don't have mine connected yet). You could also use an electric speedo, but you probably would still need an adapter to mate with the transmission output.
Tacho: No problem there, it just hooks right up. You'll need to set the switches on the back of the tach to match your cylinder count, ie, 4, 6, or 8.
Temp: I removed the stock temp sender and drilled the guts out. I then tapped the hole in the sender to match the Autometer sender and screwed it in. No problems at all with that.
Fuel: Using the stock sender worked fine, but it was very non-linear. At a half-full reading, I only have about 3-4 gallons left. I modified the stock sending unit mounting to make it fit the Autometer sender, but I haven't installed it yet (I had a spare from my junk bin). That matched the sender to the gauge, but there is still a non-linearity, as the tank itself is non-linear. Te tank tapers in the bottom half, so one inch of gas is less gallons at the bottom than it is at the top. I'll be curious to see how that works out, but it should be better than using the stock sender. E-mail me if you want details.
Oil pressure: No problem here - the Autometer electric sender screwed right in the hole where the old mechanical sender went. If you want a mechanical gauge, the fitting for it would, I imagine, screw right in also.
Ammeter: As stated above, an ameter is an ammeter, so no problem here. If you have any idea that you may want to upgrade to a larger alternator, you may want to consider a 60-0-60 amp meter instead, but if that's the case, I recommend getting a voltmeter instead. There are a lot of reason for using a voltmeter instead of an ammeter, but I don't agree with any of them. If you have no plans for upgrading your electrical system, I say stick with the ammeter. The real reason for getting away from ammeter by the auto makers was one of simple practicality. As the surrent needs went up, the wire size needed to handle it also went up. When the ammeter wires were small, it was pretty easy to connect them to the small lugs on the gauge, but if your current needs require an 8 gauge wire, for example, it get mighty hard to work with that size on a small gauge.
Hey Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
