1974 V8

[Supermutt]

Here are some additional pics of the V8 I am trying to identify. Hopefully in a week or so I may see it in person. 

[CF-Firefighter]

Looks like an 866 Thermodyne to me. If it was gold it would have been an 865 Maxidyne. 

[Supermutt]

I know it’s pretty difficult to identify with just some pics. If it’s the 866 I wonder if it’s the 375hp version.  I read somewhere that Mack put the 12spd behind the 375.  The cab interior pic looks like a 12spd. The truck is supposed to be a 74, R700. So was the 375hp version available in 74 ?  So difficult to get definitive info on the old v8’s. 

[CF-Firefighter]

I believe it was. I don’t think the 864 made it out of the 60’s. Atleast in fire trucks the 865/866 were available I think 73-79ish time frame in CF-700’s
 

Most 866’s were 375 hp. I’m sure they had some

lesser ratings for oddball stuff. 

[Supermutt]

Was the 375, 866 any better than the 864 or 865 ?  I am wondering if it’s worth picking up. I am kinda surprised at how clean it is. 

[CF-Firefighter]

865/866 are the same engine. Some different parts. One is a Thermodyne, One a Maxidyne. But physically they are identical. I believe so. I’m not an expert by any stretch but own an 865. It doesn’t leak and runs very well.  They seem built tough, just repairs are expensive and hard parts are a bit of a search. I’m not scared of mine, it’s just in a toy though it’s not a working truck. 
 

don’t think there were any huge issues. I’ve heard of people talking about rolling bearings in them after some time for prevention, an oil pump relive spring that can get weak, head gaskets if not kept torqued. But other then that nothing that I know of. 

Edited October 29, 2023 by CF-Firefighter

[Supermutt]

Might be able to pick up the whole truck for $1500. I am trying to get the vin. All I know is it was parked 3 years ago. Has a water tank on it. He said it ran good when parked. He picked up a newer water truck. 

[D-Day]

Just forward of the starter on the edge of the block above the oil pan is where the identification numbers are stamped I think cab over engines were stamped at the right rear 

[mechohaulic]

5 hours ago, CF-Firefighter said:

Looks like an 866 Thermodyne to me. If it was gold it would have been an 865 Maxidyne. 

have to agree on the thermodyne ; can't remember them being the light blue. course that's NOT the only thing I can't seem to remember lately

[mechohaulic]

4 hours ago, Supermutt said:

I know it’s pretty difficult to identify with just some pics. If it’s the 866 I wonder if it’s the 375hp version.  I read somewhere that Mack put the 12spd behind the 375.  The cab interior pic looks like a 12spd. The truck is supposed to be a 74, R700. So was the 375hp version available in 74 ?  So difficult to get definitive info on the old v8’s. 

I worked Mack trucks '69--'75 ; the 866/// 375  was around before I left. shift defiantly looks to be 12 speed wouldn't be hooked to 865 maxi. 

[mechohaulic]

this R700 :V8 topic sure has the interest for me .. back then I delivered a brand new R-700 (V-8) to a construction co in this town (watertown,CT ). doubt the co like many aren't around any more . Watertown construction ??; not dayton construction= they are still around. 

[D-Day]

The 864 was finished in 1972 and the ET 1000 did not come out until 1978 so a look at the numbers is important but it all looks good 

[fjh]

It’s likly a 375! If it was a 325 it would likly have  a six speed Trans!

[Brian L Blaylock]

It’s more than likely a endt-866 with a 12 speed but it could possibly be a endt-865 with a air shift 6 speed the engine number will be stamped on the block as described in a previous comment if it is a factory endt-866 the truck vin will start out as R-797 a truck with the endt-866 will be R-795