Specific help with rebuild mono valve 87 560SL

[ukrmh88]

I have decided that the mono valve in my 87 560SL needs to be rebuilt. I am getting random heating and cooling these cold days, and this seems to be the simplest fix with which to begin. I have done a lot of searching on this site as well as others to learn how to do it. Most say it is easy-only takes 15 minutes or so....
To replace the parts inside the valve, can this be done while the housing is still mounted on the bracket to the firewall? Does the coolant need to be drained? (probably a stupid question, but not addressed anywhere I can find!)
I greatly hesitate removing the entire valve assembly from the engine compartment because those connecting hoses are all old, and I don't want to break any of the plastic parts trying to remove the hoses from the valve.
Best price I can find on the valve is $39 + shipping on the web. In one of the threads I read somewhere, it was stated this rebuild kit can be acquired for $20. Where can I find the best price on the kit? I promise to take pictures and post them once I have accomplished this task! Thanks in advance.
Bob

[Strife]

You do NOT have to remove the valve in order to do this.

Very little will drain out (clean it up anyway, pets, etc), I didn't have any problem, but I have heard that none will drain out if you park downhill.

[rocky raccoon]

a. You will lose no coolant unless you are very sloppy.

b. No need to remove valve body BUT if hoses look fragile, replace them to avoid a catastrophe later.

c. Prices you quote look too low. A rebuild kit will probably cost $35 to $45. A complete valve assembly should be $140 to $165.

[London380sl]

This is a really easy job to do. Here's a writeup with pics on how to do it.

http://www.zianet.com/SLlover/page62g.html

My only advice is to:

1) Do it while the engine is cold.

2) Note the placement of the parts when you're taking it out and replace exactly in order.

3) When finished start the car up and let it get up to operating temp to make sure it's not leaking.

[ukrmh88]

London 380sl
The link had all of the pictures anyone would need for this job, so I will not attach any for this simple job. I looked all over the internet for a detailed explanation with pictures and could not find anything with as much detail as all have provided.
The job literally took 10 minutes inside my 40 degree garage. It is now 3 pm and 9 degrees outside, so it is really nice to have consistent heat! I purchased the valve repair kit from NAPA for $36.95 locally. This was the best price I could find anywhere and repair is leak-free. NAPA stands behind their parts and they are only a couple of miles away. Thanks again to you and the other respondents!
Bob