So the story begins when I purchased my Revo 2.5R sometime around 2006.
Changed a few things here and there as they broke and eventually got tired of the constant tuning of the 2.5R.

I decided on the OS .18TM, which, once broken in I basically tuned it once and it's been running beautifully up until I removed it for this conversion.

This all came about after driving my friends brushless Stampede. I thought, wow this thing is pretty fast, it makes almost no noise and it's still clean.

As an experiment and for fun I have tried to convert my Revo to brushless as cheaply as possible, obviously trying to avoid skimping in areas where I felt a slightly more pricey part was required. I also did not want to modify anything to permanently as I may want to change back.
What I can say is that so far the conversion seems good and I am happy with the parts that I choose.

Things removed:

2 steering servos (did single servo conversion at the same time)
Throttle servo
Receiver box & battery(receiver moved to where throttle servo was)
OS .18TM (pullstart) with exhaust and fuel tank
Brake disc (gearbox locked in 2nd, had FOC kit already as optidrive has issues)

Things purchased:

******* ********* 120A Brushless Short Course Truck ESC

S3674-2370 Brushless Inrunner (2370kv)

******* Heat Sink with Fan

******* Metal Gear Servo 60g/15.5kg/.16sec

******* 5000mAh 4S1P 14.8v 20C hardcase pack

Total $129 (including servo)

Also bought a programming card and some connectors which were quite cheap.

I decided to make a battery and ESC tray from PVC. It mounted on top of the servo mounts, radio mount and fuel tank mount.
I had to make small triangular supports in order to use the screw holes currently in the chassis.

I also made a engine mount from a piece of 50mm angle aluminium. I used 3mm at first with a gusset, however this bent in multiple places after one crash. It looks mostly due to the cutout made for the throttle linkage mount.

My second attempt used 5mm angle with a 3mm gusset. This time I moved things around a bit such that they are stronger. The throttle linkage mount was also filed flush with the rest of the mount. Seems pretty decent now, had a couple of harsh crashes and nothing moved an inch.
I also made a small spacer to support the back of the motor. It's also made from PVC, and hopefully it does something useful.

I used a bit of thermal paste when I put the heatsink on, hopefully this helps a bit with the conductivity.

I've heard of people breaking many diffs after doing brushless conversions, so I don't tighten my slipper clutch that much. The car won't wheelie from a standstill however at about 30-40 km/h the front wheels often begin to leave the ground. The car is rather fast, I'm slightly scared to drive it other than in a large open space with no trees. If the clutch is tightened the car wheelies on demand.

ESC and motor seem to stay cool.

Driving time seems about 30mins +

One strange thing I've noticed is that my range (radio range) is terrible, I'm not sure if this is due to interference from the ESC? I checked the aerial wire and it is still fine.
It's still running the old 27MHz AM radio and receiver. It's probably time to move to 2.4GHz?

Things on the way:

RPM Carriers (current bearings are shot and pivot balls have pulled out a few times)
Bearings for diffs
Spare diff
Spare driveshaft

My new body needs painting and the old one is too ugly to show

Here are a few pics:

Stripped diffs to inspect them, they still look pretty good.

First attempt on the motor mount

Second attempt on the motor mount

Motor support spacer

Sorry if some of these are slightly blurry...

Battery tray, one can see the triangular spacers I was talking about on the left