Fan belt.

[1098]

I have a 948 engine/ box/diff and speedo,removed from a scrap car. I've never experienced the 948. I often hear it's a very smooth unit. Is there a big difference on power out put,compared to the 1098 Job ?

Quite a difference:

1956–62: 948 cc A-series inline-four, 37 hp (28 kW) at 4,750 rpm and 50 lb·ft (68 N·m) at 2,500 rpm
1962–72: 1,098 cc A-series inline-four, 48 hp (36 kW) at 5,100 rpm and 60 lb·ft (81 N·m) at 2,500 rpm

But like you say, the 948cc is smoother and more rev-happy, whereas the 1098cc is a long-stroke torque-meister that doesn't like to rev beyond about 5,000 rpm.

Thanks Chipper. Must try it,just for the experience.